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  • 1.
    Agarwal, Jessica
    et al.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Vincent, J. -B
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hoefner, S.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservat 3, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, Lab Astrophys Marseille, CNRS, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC, Ctr Astrobiol, INTA, European Space Agcy,ESAC, POB 78, E-28691 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Poland..
    Barucci, M. A.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    INAF Osservat Astron Padova, Vicolo Osservat 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B.
    Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommarive 9, I-38123 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fornasier, S.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservat Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Groussin, O.
    Aix Marseille Univ, LAM, CNRS, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, LAM, CNRS, UMR 7326, F-13388 Marseille, France..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, POB 78, E-28691 Villanueva De La Cananda, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservat 3, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservat 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Acceleration of individual, decimetre-sized aggregates in the lower coma of comet 67P/Churyumov-Gerasimenko2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S78-S88Article in journal (Refereed)
    Abstract [en]

    We present observations of decimetre-sized, likely ice-containing aggregates ejected from a confined region on the surface of comet 67P/Churyumov-Gerasimenko. The images were obtained with the narrow angle camera of the Optical, Spectroscopic, and Infrared Remote Imaging System on board the Rosetta spacecraft in 2016 January when the comet was at 2 au from the Sun outbound from perihelion. We measure the acceleration of individual aggregates through a 2 h image series. Approximately 50 per cent of the aggregates are accelerated away from the nucleus, and 50 per cent towards it, and likewise towards either horizontal direction. The accelerations are up to one order of magnitude stronger than local gravity, and are most simply explained by the combined effect of gas drag accelerating all aggregates upwards, and the recoil force from asymmetric outgassing, either from rotating aggregates with randomly oriented spin axes and sufficient thermal inertia to shift the temperature maximum away from an aggregate's subsolar region, or from aggregates with variable ice content. At least 10 per cent of the aggregates will escape the gravity field of the nucleus and feed the comet's debris trail, while others may fall back to the surface and contribute to the deposits covering parts of the Northern hemisphere. The rocket force plays a crucial role in pushing these aggregates back towards the surface. Our observations show the future back fall material in the process of ejection, and provide the first direct measurement of the acceleration of aggregates in the innermost coma (<2 km) of a comet, where gas drag is still significant.

  • 2.
    Attree, N.
    et al.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Nebouy, D.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Thomas, N.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Brouet, Y.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Kuehrt, E.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Preusker, F.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Scholten, F.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Knollenberg, J.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Hartogh, P.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Rodrigo, R.
    INTA CSIC, Ctr Astrobiol, Madrid 28691, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    ESA, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany.;TU Braunschweig, Inst Geophys & Extraterrestrial Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Cremonese, G.
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B.
    Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    El-Maarry, M. R.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astronom, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Ip, W. -H
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kueppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Lazzarin, M.
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Lowry, S.
    Univ Kent, Sch Phys Sci SEPnet, Ctr Astrophys & Planetary Sci, Canterbury CT2 7NH, Kent, England..
    Marchi, S.
    Southwest Res Inst, 1050 Walnut St, Boulder, CO 80302 USA..
    Marzari, F.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Mottola, S.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Naletto, G.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.;Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Oklay, N.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, H-1121 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Shi, X.
    Tensile strength of 67P/Churyumov-Gerasimenko nucleus material from overhangs2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 611, article id A33Article in journal (Refereed)
    Abstract [en]

    We directly measured twenty overhanging cliffs on the surface of comet 67P/Churyumov-Gerasimenko extracted from the latest shape model and estimated the minimum tensile strengths needed to support them against collapse under the comet's gravity. We find extremely low strengths of around 1 Pa or less (1 to 5 Pa, when scaled to a metre length). The presence of eroded material at the base of most overhangs, as well as the observed collapse of two features and the implied previous collapse of another, suggests that they are prone to failure and that the true material strengths are close to these lower limits (although we only consider static stresses and not dynamic stress from, for example, cometary activity). Thus, a tensile strength of a few pascals is a good approximation for the tensile strength of the 67P nucleus material, which is in agreement with previous work. We find no particular trends in overhang properties either with size over the similar to 10-100 m range studied here or location on the nucleus. There are no obvious differences, in terms of strength, height or evidence of collapse, between the populations of overhangs on the two cometary lobes, suggesting that 67P is relatively homogenous in terms of tensile strength. Low material strengths are supportive of cometary formation as a primordial rubble pile or by collisional fragmentation of a small body (tens of km).

  • 3. Auger, A. -T
    et al.
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Bouley, S.
    Univ Paris 11, Lab GEOPS, Geosci Paris Sud, F-91405 Orsay, France.;Inst Mecan Celeste & Calcul Ephemerides, UMR 8028, F-75014 Paris, France..
    Gaskell, R.
    Planetary Sci Inst, Tucson, AZ 85719 USA..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Capanna, C.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid 28691, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, CISAS, I-35100 Padua, Italy..
    Cremonese, G.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W. -H
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marchi, S.
    Southwest Res Inst, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Massironi, M.
    Osserv Astron Padova, INAF, I-35121 Padua, Italy.;Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, CISAS, I-35100 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Sabau, L.
    Inst Nacl Tecn Aeroesp, Madrid 28850, Spain..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Wenzel, K. -P
    Geomorphology of the Imhotep region on comet 67P/Churyumov-Gerasimenko from OSIRIS observations2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A35Article in journal (Refereed)
    Abstract [en]

    Context. Since August 2014, the OSIRIS Narrow Angle Camera (NAC) onboard the Rosetta spacecraft has acquired high spatial resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko, down to the decimeter scale. This paper focuses on the Imhotep region, located on the largest lobe of the nucleus, near the equator. Aims. We map, inventory, and describe the geomorphology of the Imhotep region. We propose and discuss some processes to explain the formation and ongoing evolution of this region. Methods. We used OSIRIS NAC images, gravitational heights and slopes, and digital terrain models to map and measure the morphologies of Imhotep. Results. The Imhotep region presents a wide variety of terrains and morphologies: smooth and rocky terrains, bright areas, linear features, roundish features, and boulders. Gravity processes such as mass wasting and collapse play a significant role in the geomorphological evolution of this region. Cometary processes initiate erosion and are responsible for the formation of degassing conduits that are revealed by elevated roundish features on the surface. We also propose a scenario for the formation and evolution of the Imhotep region; this implies the presence of large primordial voids inside the nucleus, resulting from its formation process.

  • 4.
    Barucci, M. A.
    et al.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Filacchione, G.
    INAF IAPS, I-00133 Rome, Italy..
    Fornasier, S.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Raponi, A.
    INAF IAPS, I-00133 Rome, Italy..
    Deshapriya, J. D. P.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Tosi, F.
    INAF IAPS, I-00133 Rome, Italy..
    Feller, C.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Ciarniello, M.
    INAF IAPS, I-00133 Rome, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Capaccioni, F.
    INAF IAPS, I-00133 Rome, Italy..
    Pommerol, A.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, I-35122 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Merlin, F.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Vincent, J. -B
    Fulchignoni, M.
    Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Guilbert-Lepoutre, A.
    Observ Sci Univers, F-25000 Besancon, France..
    Perna, D.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Capria, M. T.
    INAF IAPS, I-00133 Rome, Italy..
    Hasselmann, P. H.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Rousseau, B.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Bockelee-Morvan, D.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Lamy, P. L.
    Aix Marseille Univ, F-13388 Marseille 13, France..
    De Sanctis, C.
    INAF IAPS, I-00133 Rome, Italy..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Univ Bern, Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Erard, S.
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Leyrat, C.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Drossart, P.
    UPMC Univ Paris 06, Univ Paris Diderot, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Arnold, G.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Bertaux, J. -L
    Bertini, I.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Cerroni, P.
    INAF IAPS, I-00133 Rome, Italy..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy..
    Davidsson, B. J. R.
    JPL, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fonti, S.
    Univ Salento, Dipartimento Fis, Lecce, LE, Italy..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34143 Trieste, Italy..
    Groussin, O.
    CNRS, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    CNRS, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Kappel, D.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    ESA ESAC, POB 78, Villanueva De La Canada 28691, Spain..
    Lara, L.
    CSIC, Inst Astrofis Andalucia, Granada 18080, Spain..
    Lazzarin, M.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, Granada 18080, Spain..
    Mancarella, F.
    Univ Salento, Dipartimento Fis, Lecce, LE, Italy..
    Marzari, F.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Mottola, S.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Palomba, E.
    INAF IAPS, I-00133 Rome, Italy..
    Quirico, E.
    UJF Grenoble 1, CNRS INSU, F-38400 St Martin Dheres, France..
    Schmitt, B.
    UJF Grenoble 1, CNRS INSU, F-38400 St Martin Dheres, France..
    Thomas, N.
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Detection of exposed H2O ice on the nucleus of comet 67P/Churyumov-Gerasimenko as observed by Rosetta OSIRIS and VIRTIS instruments2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 595, article id A102Article in journal (Refereed)
    Abstract [en]

    Context. Since the orbital insertion of the Rosetta spacecraft, comet 67P/Churyumov-Gerasimenko (67P) has been mapped by OSIRIS camera and VIRTIS spectro-imager, producing a huge quantity of images and spectra of the comet's nucleus. Aims. The aim of this work is to search for the presence of H2O on the nucleus which, in general, appears very dark and rich in dehydrated organic material. After selecting images of the bright spots which could be good candidates to search for H2O ice, taken at high resolution by OSIRIS, we check for spectral cubes of the selected coordinates to identify these spots observed by VIRTIS. Methods. The selected OSIRIS images were processed with the OSIRIS standard pipeline and corrected for the illumination conditions for each pixel using the Lommel-Seeliger disk law. The spots with higher I/F were selected and then analysed spectrophotometrically and compared with the surrounding area. We selected 13 spots as good targets to be analysed by VIRTIS to search for the 2 mu m absorption band of water ice in the VIRTIS spectral cubes. Results. Out of the 13 selected bright spots, eight of them present positive H2O ice detection on the VIRTIS data. A spectral analysis was performed and the approximate temperature of each spot was computed. The H2O ice content was confirmed by modeling the spectra with mixing (areal and intimate) of H2O ice and dark terrain, using Hapke's radiative transfer modeling. We also present a detailed analysis of the detected spots.

  • 5.
    Bertini, I.
    et al.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lamy, P.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France..
    Bertaux, J. -L
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trent, UNITN, I-38100 Trento, Italy..
    Ferri, F.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France.;Univ Paris Diderot, Sorbonne Paris Cite, F-75205 Paris 13, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, I-34143 Trieste, Italy..
    Giacomini, L.
    Univ Padua, Dept Geosci, I-35131 Padua, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Magrin, S.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Dept Geosci, I-35131 Padua, Italy..
    Michalik, H.
    Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Mottola, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Search for satellites near comet 67P/Churyumov-Gerasimenko using Rosetta/OSIRIS images2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A19Article in journal (Refereed)
    Abstract [en]

    Context. The European Space Agency Rosetta mission reached and started escorting its main target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, at the beginning of August 2014. Within the context of solar system small bodies, satellite searches from approaching spacecraft were extensively used in the past to study the nature of the visited bodies and their collisional environment. Aims. During the approaching phase to the comet in July 2014, the OSIRIS instrument onboard Rosetta performed a campaign aimed at detecting objects in the vicinity of the comet nucleus and at measuring these objects' possible bound orbits. In addition to the scientific purpose, the search also focused on spacecraft security to avoid hazardous material in the comet's environment. Methods. Images in the red spectral domain were acquired with the OSIRIS Narrow Angle Camera, when the spacecraft was at a distance between 5785 km and 5463 km to the comet, following an observational strategy tailored to maximize the scientific outcome. From the acquired images, sources were extracted and displayed to search for plausible displacements of all sources from image to image. After stars were identified, the remaining sources were thoroughly analyzed. To place constraints on the expected displacements of a potential satellite, we performed Monte Carlo simulations on the apparent motion of potential satellites within the Hill sphere. Results. We found no unambiguous detections of objects larger than similar to 6 m within similar to 20 km and larger than similar to 1 m between similar to 20 km and similar to 110 km from the nucleus, using images with an exposure time of 0.14 s and 1.36 s, respectively. Our conclusions are consistent with independent works on dust grains in the comet coma and on boulders counting on the nucleus surface. Moreover, our analysis shows that the comet outburst detected at the end of April 2014 was not strong enough to eject large objects and to place them into a stable orbit around the nucleus. Our findings underline that it is highly unlikely that large objects survive for a long time around cometary nuclei.

  • 6.
    Bodewits, D.
    et al.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;Akad Wissensch Gottingen, D-37077 Gottingen, Germany..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lin, Z. -Y
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Snodgrass, C.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Barucci, M. A.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, E-28691 Villanueva De La Canada, Madrid, Spain..
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland..
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, HU-1525 Budapest, Hungary..
    Vincent, J. -B
    Changes in the physical environment of the inner coma of 67p/churyumov-gerasimenko with decreasing heliocentric distance2016In: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, no 5, article id 130Article in journal (Refereed)
    Abstract [en]

    The Wide Angle Camera of the OSIRIS instrument on board the Rosetta spacecraft is equipped with several narrow-band filters that are centered on the emission lines and bands of various fragment species. These are used to determine the evolution of the production and spatial distribution of the gas in the inner coma of comet 67P with time and heliocentric distance, here between 2.6 and 1.3 au pre-perihelion. Our observations indicate that the emission observed in the OH, OI, CN, NH, and NH2 filters is mostly produced by dissociative electron impact excitation of different parent species. We conclude that CO2 rather than H2O is a significant source of the [OI] 630 nm emission. A strong plume-like feature observed in the CN and OI filters is present throughout our observations. This plume is not present in OH emission and indicates a local enhancement of the CO2/H2O ratio by as much as a factor of 3. We observed a sudden decrease in intensity levels after 2015 March, which we attribute to decreased electron temperatures in the first few kilometers above the surface of the nucleus.

  • 7.
    Cremonese, G.
    et al.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35131 Padua, Italy..
    Simioni, E.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35131 Padua, Italy.;UOS Padova LUXOR, CNR IFN, Via Trasea 7, I-35131 Padua, Italy..
    Ragazzoni, R.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35131 Padua, Italy..
    Bertini, I.
    Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    La Forgia, F.
    Univ Padua, Dipartimento Fis & Astron, Vic Osservatorio 3, I-35122 Padua, Italy..
    Pajola, M.
    Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fornasier, S.
    Univ Paris 06, Sorbonne Paris Cite, Univ Paris Diderot, Univ Sorbonne,CNRS,PSL Res Univ,Observ Paris,LESI, 5 Pl J Janssen, F-92195 Meudon, France..
    Lazzarin, M.
    Univ Padua, Dipartimento Fis & Astron, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lucchetti, A.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dipartimento Fis & Astron, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, CNRS LAM, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support ffi, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Estraterr Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barucci, M. A.
    Univ Paris 06, Sorbonne Paris Cite, Univ Paris Diderot, Univ Sorbonne,CNRS,PSL Res Univ,Observ Paris,LESI, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Da Deppo, V.
    UOS Padova LUXOR, CNR IFN, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    De Cecco, M.
    Univ Trento, Via Sommarive 9, I-38123 Trento, Italy..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS LAM, UMR 7326, F-13388 Marseille, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Hviid, S. F.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS LAM, UMR 7326, F-13388 Marseille, France..
    Knollenberg, J.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. -R
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    Kuert, E.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Magrin, S.
    Univ Padua, Dipartimento Fis & Astron, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Marzari, F.
    Univ Padua, Dipartimento Fis & Astron, Vic Osservatorio 3, I-35122 Padua, Italy..
    Mottola, S.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Trento, Via Sommarive 9, I-38123 Trento, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Preusker, F.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    Inst fur Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J-B
    Photometry of dust grains of comet 67P and connection with nucleus regions2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 588, article id A59Article in journal (Refereed)
    Abstract [en]

    Aims. Multiple pairs of high-resolution images of the dust coma of comet 67P/Churyumov-Gerasimenko have been collected by OSIRIS onboard Rosetta allowing extraction and analysis of dust grain tracks. Methods. We developed a quasi automatic method to recognize and to extract dust tracks in the Osiris images providing size, FWHM and photometric data. The dust tracks characterized by a low signal-to-noise ratio were checked manually. We performed the photometric analysis of 70 dust grain tracks observed on two different Narrow Angle Camera images in the two filters F24 and F28, centered at lambda = 480.7 nm and at lambda = 743.7 nm, respectively, deriving the color and the reddening of each one. We then extracted several images of the nucleus observed with the same filters and with the same phase angle to be compared with the dust grain reddening. Results. Most of the dust grain reddening is very similar to the nucleus values, confirming they come from the surface or subsurface layer. The histogram of the dust grain reddening has a secondary peak at negative values and shows some grains with values higher than the nucleus, suggesting a different composition from the surface grains. One hypothesis comes from the negative values point at the presence of hydrated minerals in the comet.

  • 8.
    Davidsson, Björn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support Off, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;Akad Wissensch Gottingen, D-37077 Gottingen, Germany..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, LESIA Observ Paris, CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi Att Spaziali Giuseppe Colombo CI, I-35131 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    Osserv Astron Padova, INAF, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Debei, S.
    Univ Trento, I-38100 Trento, Italy..
    De Cecco, M.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, LESIA Observ Paris, CNRS, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lowry, S.
    Univ Kent, Ctr Astrophys & Planetary Sci, Sch Phys Sci, Canterbury CT2 7NH, Kent, England..
    Magrin, S.
    Univ Padua, Dept Phys & Astron, I-35131 Padua, Italy..
    Marzari, E.
    Univ Padua, Dept Phys & Astron, I-35131 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Moissl-Fraund, R.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    Naletto, G.
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi Att Spaziali Giuseppe Colombo CI, I-35131 Padua, Italy..
    Snodgrass, C.
    Open Univ, Planetary & Space Sci, Dept Phys Sci, Milton Keynes MK7 6AA, Bucks, England..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A16Article in journal (Refereed)
    Abstract [en]

    Context. We investigate the dust coma within the Hill sphere of comet 67P/Churyumov-Gerasimenko. Aims. We aim to determine osculating orbital elements for individual distinguishable but unresolved slow-moving grains in the vicinity of the nucleus. In addition, we perform photometry and constrain grain sizes. Methods. We performed astrometry and photometry using images acquired by the OSIRIS Wide Angle Camera on the European Space Agency spacecraft Rosetta. Based on these measurements, we employed standard orbit determination and orbit improvement techniques. Results. Orbital elements and effective diameters of four grains were constrained, but we were unable to uniquely determine them. Two of the grains have light curves that indicate grain rotation. Conclusions. The four grains have diameters nominally in the range 0.14-0.50 m. For three of the grains, we found elliptic orbits, which is consistent with a cloud of bound particles around the nucleus. However, hyperbolic escape trajectories cannot be excluded for any of the grains, and for one grain this is the only known option. One grain may have originated from the surface shortly before observation. These results have possible implications for the understanding of the dispersal of the cloud of bound debris around comet nuclei, as well as for understanding the ejection of large grains far from the Sun.

  • 9.
    Davidsson, Björn J. R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Gutierrez, Pedro J.
    Groussin, Olivier
    A'Hearn, Michael F.
    Farnham, Tony
    Feaga, Lori M.
    Kelley, Michael S.
    Klaasen, Kenneth P.
    Merlin, Frederic
    Protopapa, Silvia
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Sunshine, Jessica M.
    Thomas, Peter C.
    Thermal inertia and surface roughness of Comet 9P/Tempel 12013In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 224, no 1, p. 154-171Article in journal (Refereed)
    Abstract [en]

    Re-calibrated near-infrared spectroscopy of the resolved nucleus of Comet 9P/Tempel 1 acquired by the Deep Impact spacecraft has been analyzed by utilizing the post-Stardust-NExT nucleus shape model and spin pole solution, as well as a novel thermophysical model that explicitly accounts for small-scale surface roughness and thermal inertia. We find that the thermal inertia varies measurably across the surface, and that thermal emission from certain regions only can be reproduced satisfactory if surface roughness is accounted for. Particularly, a scarped/pitted terrain that experienced morning sunrise during the flyby is measurably rough (Hapke mean slope angle similar to 45 degrees) and has a thermal inertia of at most 50J m(-2) K-1 s(-1/2), but probably much lower. However, thick layered terrain and thin layered terrain experiencing local noon during the flyby have a substantially larger thermal inertia, reaching 150J m(-2) K-1 s(-1/2) if the surface is as rough as the scarped/pitted terrain, but 200J m(-2) K-1 s(-1/2) if the terrain is considered locally flat. Furthermore, the reddening of the nucleus near-infrared 1.5-2.2 gm spectrum varies between morphological units, being reddest for thick layered terrain (median value 3.4% k angstrom(-1)) and most neutral for the smooth terrain known to contain surface water ice (median value 3.1% k angstrom(-1)). Thus, Comet 9P/Tempel 1 is heterogeneous in terms of both thermophysical and optical properties, due to formation conditions and/or post-formation processing. 

  • 10.
    Davidsson, Björn J. R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Gutiérrez, Pedro J.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Nucleus properties of Comet 9P/Tempel 1 estimated from non-gravitational force modeling2007In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 187, no 1, p. 306-320Article in journal (Refereed)
    Abstract [en]

    The nucleus mass and bulk density of Comet 9P/Tempel 1 have been estimated by utilizing the non-gravitational force modeling technique. Here, the water production rates and non-gravitational perturbations of the orbit are calculated for a large number of model nuclei with different surface ice distribution patterns. By requiring that the empirical water production rate curve is reproduced, a subset of model nuclei are selected, for which masses are calculated by demanding that empirical non-gravitational changes of the orbital period and in the longitude of perihelion (per revolution) are reproduced. We obtain a mass M=5.8(±1.6)×1013 kg, and a bulk density , which compares very well with measurements made by the Deep Impact Science Team. The main goal of the current work is therefore to demonstrate functionality of an indirect method, i.e., mass estimation through non-gravitational force modeling, by comparing such results to ground truth data. Furthermore, the thermal inertia of active areas is estimated as 30–100 MKS, using a comparatively realistic thermophysical model (although a value in the range 100–350 MKS is obtained with a more simple model). An active area fraction of 3% is predicted, and these areas are probably confined to the northern hemisphere, being located close to the cometary equator.

  • 11.
    Davidsson, Björn J. R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Surface roughness and three-dimensional heat conduction in thermophysical models2014In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 243, p. 58-77Article in journal (Refereed)
    Abstract [en]

    A thermophysical model is presented that considers surface roughness, cast shadows, multiple or single scattering of radiation, visual and thermal infrared self heating, as well as heat conduction in one or three dimensions. The code is suitable for calculating infrared spectral energy distributions for spatially resolved or unresolved minor Solar System bodies without significant atmospheres or sublimation, such as the Moon, Mercury, asteroids, irregular satellites or inactive regions on comet nuclei. It is here used to explore the effects of surface roughness on spatial scales small enough for heat conduction to erase lateral temperature gradients. Analytically derived corrections to one-dimensional models that reproduce the results of three-dimensional modeling are presented. We find that the temperature of terrains with such small-scale roughness is identical to that of smooth surfaces for certain types of topographies and non-scattering material. However, systematic differences between smooth and rough terrains are found for scattering materials, or topographies with prominent positive relief. Contrary to common beliefs, the roughness on small spatial scales may therefore affect the thermal emission of Solar System bodies.

  • 12.
    Davidsson, Björn J. R.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Bandfield, Joshua L.
    Groussin, Olivier
    Gutierrez, Pedro J.
    Wilska, Magdalena
    Capria, Maria Teresa
    Emery, Joshua P.
    Helbert, Joern
    Jorda, Laurent
    Maturilli, Alessandro
    Mueller, Thomas G.
    Interpretation of thermal emission. I. The effect of roughness for spatially resolved atmosphereless bodies2015In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 252, p. 1-21Article in journal (Refereed)
    Abstract [en]

    Spacecraft observations of atmosphereless Solar System bodies, combined with thermophysical modeling, provide important information about the thermal inertia and degree of surface roughness of these bodies. The thermophysical models rely on various methods of generating topography, the most common being the concave spherical segment. We here compare the properties of thermal emission for a number of different topographies - concave spherical segments, random Gaussians, fractals and parallel sinusoidal trenches - for various illumination and viewing geometries, degrees of surface roughness and wavelengths. We find that the thermal emission is strongly dependent on roughness type, even when the degrees of roughness are identical, for certain illumination and viewing geometries. The systematic usage of any single topography model may therefore bias determinations of thermal inertia and level of roughness. We outline strategies that may be employed during spacecraft observations to disentangle thermal inertia, level of roughness and type of topography. We also compare the numerically complex and time consuming full-scale thermophysical models with a simplified statistical approach, which is fairly easy to implement and quick to run. We conclude that the simplified statistical approach is similar to thermophysical models for cases tested here, which enables the user to analyze huge amounts of spectral data at a low numerical cost.

  • 13.
    Davidsson, Björn
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Jet Prop Lab, MS 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Via Marzolo 8, I-35131 Padua, Italy..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAN Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    A'Hearn, M. F.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;Akad Wissensch Gottingen, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Auger, A. -T
    El-Maarry, M. R.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Massironi, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy.;Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy..
    Snodgrass, C.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Vincent, J. -B
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    ESA, European Space Res & Technol Ctr, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Mesiano 77, I-38100 Trento, Italy..
    Feller, C.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Fulle, M.
    INAF, Osservatorio Astron, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Hoefner, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Ip, W. -H
    Jorda, L.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, Madrid 28691, Spain..
    La Forgia, F.
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Lazzarin, M.
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Moissl-Fraund, R.
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.;ESA, European Space Astron Ctr, Operat Dept, POB 78, Madrid 28691, Spain..
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    The primordial nucleus of comet 67P/Churyumov-Gerasimenko2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 592, article id A63Article in journal (Refereed)
    Abstract [en]

    Context. We investigate the formation and evolution of comet nuclei and other trans-Neptunian objects (TNOs) in the solar nebula and primordial disk prior to the giant planet orbit instability foreseen by the Nice model. Aims. Our goal is to determine whether most observed comet nuclei are primordial rubble-pile survivors that formed in the solar nebula and young primordial disk or collisional rubble piles formed later in the aftermath of catastrophic disruptions of larger parent bodies. We also propose a concurrent comet and TNO formation scenario that is consistent with observations. Methods. We used observations of comet 67P/Churyumov-Gerasimenko by the ESA Rosetta spacecraft, particularly by the OSIRIS camera system, combined with data from the NASA Stardust sample-return mission to comet 81P/Wild 2 and from meteoritics; we also used existing observations from ground or from spacecraft of irregular satellites of the giant planets, Centaurs, and TNOs. We performed modeling of thermophysics, hydrostatics, orbit evolution, and collision physics. Results. We find that thermal processing due to short-lived radionuclides, combined with collisional processing during accretion in the primordial disk, creates a population of medium-sized bodies that are comparably dense, compacted, strong, heavily depleted in supervolatiles like CO and CO2; they contain little to no amorphous water ice, and have experienced extensive metasomatism and aqueous alteration due to liquid water. Irregular satellites Phoebe and Himalia are potential representatives of this population. Collisional rubble piles inherit these properties from their parents. Contrarily, comet nuclei have low density, high porosity, weak strength, are rich in supervolatiles, may contain amorphous water ice, and do not display convincing evidence of in situ metasomatism or aqueous alteration. We outline a comet formation scenario that starts in the solar nebula and ends in the primordial disk, that reproduces these observed properties, and additionally explains the presence of extensive layering on 67P/Churyumov-Gerasimenko (and on 9P/Tempel 1 observed by Deep Impact), its bi-lobed shape, the extremely slow growth of comet nuclei as evidenced by recent radiometric dating, and the low collision probability that allows primordial nuclei to survive the age of the solar system. Conclusions. We conclude that observed comet nuclei are primordial rubble piles, and not collisional rubble piles. We argue that TNOs formed as a result of streaming instabilities at sizes below similar to 400 km and that similar to 350 of these grew slowly in a low-mass primordial disk to the size of Triton, Pluto, and Eris, causing little viscous stirring during growth. We thus propose a dynamically cold primordial disk, which prevented medium-sized TNOs from breaking into collisional rubble piles and allowed the survival of primordial rubble-pile comets. We argue that comets formed by hierarchical agglomeration out of material that remained after TNO formation, and that this slow growth was a necessity to avoid thermal processing by short-lived radionuclides that would lead to loss of supervolatiles, and that allowed comet nuclei to incorporate similar to 3 Myr old material from the inner solar system.

  • 14.
    Deshapriya, J. D. P.
    et al.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Barucci, M. A.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Fornasier, S.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Feller, C.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Hasselmann, P. H.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Reserch Ctr, Poland.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B. J. R.
    JPL, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Debei, S.
    Univ Padua, Dept Mech Engn, Via Venezia 1, I-35131 Padua, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy..
    Fulle, M.
    INAF, Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Groussin, O.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, R.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA, ESAC, POB 78, E-28691 Villanueva De La Canada, Spain..
    Lara, L.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Mottola, S.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Perna, D.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Pommerol, A.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Spectrophotometry of the Khonsu region on the comet 67P/Churyumov-Gerasimenko using OSIRIS instrument images2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S274-S286Article in journal (Refereed)
    Abstract [en]

    Our work focuses on the spectrophotometric analysis of selected terrain and bright patches in the Khonsu region on the comet 67P/Churyumov-Gerasimenko. Despite the variety of geological features, their spectrophotometric properties appear to indicate a similar composition. It is noticeable that the smooth areas in Khonsu possess similar spectrophotometric behaviour to some other regions of the comet. We observed bright patches on Khonsu with an estimation of >40 per cent of normal albedo and suggest that they are associated with H2O ice. One of the studied bright patches has been observed to exist on the surface for more than 5 months without a major decay of its size, implying the existence of potential sub-surface icy layers. Its location may be correlated with a cometary outburst during the perihelion passage of the comet in 2015 August, and we interpret it to have triggered the surface modifications necessary to unearth the stratified icy layers beneath the surface. A boulder analysis on Khonsu leads to a power-law index of -3.1 + 0.2/-0.3 suggesting a boulder formation, shaped by varying geological processes for different morphological units.

  • 15.
    Deshapriya, J. D. P.
    et al.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Barucci, M. A.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Fornasier, S.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Hasselmann, P. H.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Feller, C.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Sierks, H.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Lucchetti, A.
    INAF OAPD, Astron Observ Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Pajola, M.
    NASA, Ames Res Ctr, Mountain View, CA 94035 USA.
    Oklay, N.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Mottola, S.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Masoumzadeh, N.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Tubiana, C.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Guettler, C.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Barbieri, C.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Lamy, P. L.
    Aix Marseille Univ, Lab Astrophys Marseille UMR 7326, CNRS, F-13388 Marseille 13, France.
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland.
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. Polish Acad Sci, Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland.
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Boudreault, S.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Cremonese, G.
    INAF OAPD, Astron Observ Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.
    Davidsson, B. J. R.
    NASA, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA.
    Debei, S.
    Univ Padua, Dipartimento Ingn Meccan, Via Venezia 1, I-35131 Padua, Italy.
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy.
    Deller, J.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Fulle, M.
    INAF, Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy.
    Groussin, O.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain.
    Hoang, H. V.
    Univ Paris 06, Sorbonne Univ, Univ Paris Diderot,LESIA,CNRS, Sorbonne Paris Cite,PSL Res Univ,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.
    Hviid, S. F.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan.
    Jorda, L.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany.
    Knollenberg, J.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kramm, R.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kuehrt, E.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kuppers, M.
    ESA ESAC, POB 78, Villanueva De La Canada 28691, Spain.
    Lara, L.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain.
    Lazzarin, M.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain.
    Marzari, F.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Naletto, G.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy;Univ Padua, Ctr Ateneo & Attivita Spaziali Giuseppe Colombo C, Via Venezia 15, I-35131 Padua, Italy;Univ Padua, Dipartimento Ingn Informaz, Padua, Italy.
    Preusker, F.
    DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Shi, X.
    Max Planck Inst Sonnensystemforsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.
    Vincent, J. -B
    Exposed bright features on the comet 67P/Churyumov-Gerasimenko: distribution and evolution2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 613, article id A36Article in journal (Refereed)
    Abstract [en]

    Context. Since its arrival at the comet 67P/Churyumov-Gerasimenko in August 2014, the Rosetta spacecraft followed the comet as it went past the perihelion and beyond until September 2016. During this time there were many scientific instruments operating on board Rosetta to study the comet and its evolution in unprecedented detail. In this context, our study focusses on the distribution and evolution of exposed bright features that have been observed by OSIRIS, which is the scientific imaging instrument aboard Rosetta. Aims. We envisage investigating various morphologies of exposed bright features and the mechanisms that triggered their appearance. Methods. We co-registered multi-filter observations of OSIRIS images that are available in reflectance. The Lommel-Seeliger disk function was used to correct for the illumination conditions and the resulting colour cubes were used to perform spectrophotometric analyses on regions of interest. Results. We present a catalogue of 57 exposed bright features observed on the nucleus of the comet, all of which are attributed to the presence of H2O ice on the comet. Furthermore, we categorise these patches under four different morphologies and present geometric albedos for each category. Conclusions. Although the nucleus of 67P/Churyumov-Gerasimenko appears to be dark in general, there are localised H2O ice sources on the comet. Cometary activity escalates towards the perihelion passage and reveals such volatile ices. We propose that isolated H2O ice patches found in smooth terrains in regions, such as Imhotep, Bes, and Hapi, result from frost as an aftermath of the cessation of the diurnal water cycle on the comet as it recedes from perihelion. Upon the comet's return to perihelion, such patches are revealed when sublimation-driven erosion removes the thin dust layers that got deposited earlier. More powerful activity sources such as cometary outbursts are capable of revealing much fresher, less contaminated H2O ice that is preserved with consolidated cometary material, as observed on exposed patches resting on boulders. This is corroborated by our albedo calculations that attribute higher albedos for bright features with formations related to outbursts.

  • 16.
    Dones, Luke
    et al.
    SW Res Inst, Boulder, CO 80302 USA..
    Brasser, Ramon
    Tokyo Inst Technol, Earth Life Sci Inst, Meguro Ku, Tokyo 1528550, Japan..
    Kaib, Nathan
    Univ Oklahoma, HL Dodge Dept Phys & Astron, Norman, OK 73019 USA..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    Origin and Evolution of the Cometary Reservoirs2015In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 197, no 1-4, p. 191-269Article, review/survey (Refereed)
    Abstract [en]

    Comets have three known reservoirs: the roughly spherical Oort Cloud (for long-period comets), the flattened Kuiper Belt (for ecliptic comets), and, surprisingly, the asteroid belt (for main-belt comets). Comets in the Oort Cloud were thought to have formed in the region of the giant planets and then placed in quasi-stable orbits at distances of thousands or tens of thousands of AU through the gravitational effects of the planets and the Galaxy. The planets were long assumed to have formed in place. However, the giant planets may have undergone two episodes of migration. The first would have taken place in the first few million years of the Solar System, during or shortly after the formation of the giant planets, when gas was still present in the protoplanetary disk around the Sun. The Grand Tack (Walsh et al. in Nature 475:206-209, 2011) models how this stage of migration could explain the low mass of Mars and deplete, then repopulate the asteroid belt, with outer-belt asteroids originating between, and outside of, the orbits of the giant planets. The second stage of migration would have occurred later (possibly hundreds of millions of years later) due to interactions with a remnant disk of planetesimals, i.e., a massive ancestor of the Kuiper Belt. Safronov (Evolution of the Protoplanetary Cloud and Formation of the Earth and the Planets, 1969) and Fernandez and Ip (Icarus 58:109-120, 1984) proposed that the giant planets would have migrated as they interacted with leftover planetesimals; Jupiter would have moved slightly inward, while Saturn and (especially) Uranus and Neptune would have moved outward from the Sun. Malhotra (Nature 365:819-821, 1993) showed that Pluto's orbit in the 3:2 resonance with Neptune was a natural outcome if Neptune captured Pluto into resonance while it migrated outward. Building on this work, Tsiganis et al. (Nature 435:459-461, 2005) proposed the Nice model, in which the giant planets formed closer together than they are now, and underwent a dynamical instability that led to a flood of comets and asteroids throughout the Solar System (Gomes et al. in Nature 435:466-469, 2005b). In this scenario, it is somewhat a matter of luck whether an icy planetesimal ends up in the Kuiper Belt or Oort Cloud (Brasser and Morbidelli in Icarus 225:40-49, 2013), as a Trojan asteroid (Morbidelli et al. in Nature 435:462-465, 2005; NesvornA1/2 and VokrouhlickA1/2 in Astron. J. 137:5003-5011, 2009; NesvornA1/2 et al. in Astrophys. J. 768:45, 2013), or as a distant "irregular" satellite of a giant planet (NesvornA1/2 et al. in Astron. J. 133:1962-1976, 2007). Comets could even have been captured into the asteroid belt (Levison et al. in Nature 460:364-366, 2009). The remarkable finding of two "inner Oort Cloud" bodies, Sedna and 2012 , with perihelion distances of 76 and 81 AU, respectively (Brown et al. in Astrophys. J. 617:645-649, 2004; Trujillo and Sheppard in Nature 507:471-474, 2014), along with the discovery of other likely inner Oort Cloud bodies (Chen et al. in Astrophys. J. Lett. 775:8, 2013; Brasser and Schwamb in Mon. Not. R. Astron. Soc. 446:3788-3796, 2015), suggests that the Sun formed in a denser environment, i.e., in a star cluster (Brasser et al. in Icarus 184:59-82, 2006, 191:413-433, 2007, 217:1-19, 2012b; Kaib and Quinn in Icarus 197:221-238, 2008). The Sun may have orbited closer or further from the center of the Galaxy than it does now, with implications for the structure of the Oort Cloud (Kaib et al. in Icarus 215:491-507, 2011). We focus on the formation of cometary nuclei; the orbital properties of the cometary reservoirs; physical properties of comets; planetary migration; the formation of the Oort Cloud in various environments; the formation and evolution of the Kuiper Belt and Scattered Disk; and the populations and size distributions of the cometary reservoirs. We close with a brief discussion of cometary analogs around other stars and a summary.

  • 17.
    Drolshagen, E.
    et al.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 114, D-26111 Oldenburg, Germany..
    Ott, T.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 114, D-26111 Oldenburg, Germany..
    Koschny, D.
    ESA ESTEC, NL-2201 AZ Noordwijk, Netherlands.;Tech Univ Munich, Chair Astronaut, Munich, Germany..
    Guetler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. I.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC, INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    A'Hearn, M. F.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.;Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Barucci, M. A.
    Sorbonne Univ, UPMC Univ Paris 06, PSL Res Univ, LESIA,Observ Paris,CNRS,Univ Paris Diderot,Sorbon, 5 Pl Jules Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Feller, C.
    Fornasier, S.
    Fulle, M.
    INAF, Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Groussin, O.
    Aix Marseille Univ, CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curier, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Hofmann, M.
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curier, F-13388 Marseille, France..
    Keller, H. U.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Lazzarin, M.
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Marzari, F.
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Shi, X.
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland..
    Poppe, B.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 114, D-26111 Oldenburg, Germany..
    Distance determination method of dust particles using Rosetta OSIRIS NAC and WAC data2017In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 143, p. 256-264Article in journal (Refereed)
    Abstract [en]

    The ESA Rosetta spacecraft has been tracking its target, the Jupiter-family comet 67P/Churyumov-Gerasimenko, in close vicinity for over two years. It hosts the OSIRIS instruments: the Optical, Spectroscopic, and Infrared Remote Imaging System composed of two cameras, see e.g. Keller et al. (2007). In some imaging sequences dedicated to observe dust particles in the comet's coma, the two cameras took images at the same time. The aim of this work is to use these simultaneous double camera observations to calculate the dust particles' distance to the spacecraft. As the two cameras are mounted on the spacecraft with an offset of 70 cm, the distance of particles observed by both cameras can be determined by a shift of the particles' apparent trails on the images. This paper presents first results of the ongoing work, introducing the distance determination method for the OSIRIS instrument and the analysis of an example particle. We note that this method works for particles in the range of about 500-6000 m from the spacecraft.

  • 18.
    El-Maarry, M. R.
    et al.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Giacomini, L.
    Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, I-35122 Padua, Italy..
    Marschall, R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Gracia-Berna, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    INAF 78Osservatorio Astron, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Rodrigo, R.
    Int Space Sci Inst, CH-3012 Bern, Switzerland.;CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, I-35122 Padua, Italy..
    Besse, S.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    INAF 78Osservatorio Astron, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Fornasier, S.
    CNRS UVSQ IPSL, LATMOS, F-78280 Guyancourt, France..
    Fulle, M.
    INAF Osservatorio Astron, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Lab Astrophys Marseille, F-13388 Marseille 13, France..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Kueppers, M.
    European Space Astron Ctr ESA, Sci Support Off, Madrid 28691, Spain..
    La Forgia, F.
    INAF 78Osservatorio Astron, I-35122 Padua, Italy..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lazzarin, M.
    INAF 78Osservatorio Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Marchi, S.
    SW Res Inst, Solar Syst Explorat Res Virtual Inst, Boulder, CO 80302 USA..
    Marzari, F.
    INAF 78Osservatorio Astron, I-35122 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, I-35122 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Preusker, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Scholten, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A26Article in journal (Refereed)
    Abstract [en]

    Aims. The OSIRIS camera onboard the Rosetta spacecraft has been acquiring images of the comet 67P/Churyumov-Gerasimenko (67P)'s nucleus at spatial resolutions down to similar to 0.17 m/px ever since Aug. 2014. These images have yielded unprecedented insight into the morphological diversity of the comet's surface. This paper presents an overview of the regional morphology of comet 67P. Methods. We used the images that were acquired at orbits similar to 20-30 km from the center of the comet to distinguish different regions on the surface and introduce the basic regional nomenclature adopted by all papers in this Rosetta special feature that address the comet's morphology and surface processes. We used anaglyphs to detect subtle regional and topographical boundaries and images from close orbit (similar to 10 km from the comet's center) to investigate the fine texture of the surface. Results. Nineteen regions have currently been defined on the nucleus based on morphological and/or structural boundaries, and they can be grouped into distinctive region types. Consolidated, fractured regions are the most common region type. Some of these regions enclose smooth units that appear to settle in gravitational sinks or topographically low areas. Both comet lobes have a significant portion of their surface covered by a dusty coating that appears to be recently placed and shows signs of mobilization by aeolian-like processes. The dusty coatings cover most of the regions on the surface but are notably absent from a couple of irregular large depressions that show sharp contacts with their surroundings and talus-like deposits in their interiors, which suggests that short-term explosive activity may play a significant role in shaping the comet's surface in addition to long-term sublimation loss. Finally, the presence of layered brittle units showing signs of mechanical failure predominantly in one of the comet's lobes can indicate a compositional heterogeneity between the two lobes.

  • 19.
    El-Maarry, M. Ramy
    et al.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80301 USA..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Auger, A. -T
    Davidsson, B.
    Jet Prop Lab, Pasadena, CA 91109 USA..
    Hu, X.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Fornasier, S.
    Sorbonne Univ, Univ Paris Diderot, PSL Res Univ,CNRS,LESIA, UPMC Univ Paris 06,Observ Paris,Sorbonne Paris Ci, F-92195 Meudon, France..
    Feller, C.
    Sorbonne Univ, Univ Paris Diderot, PSL Res Univ,CNRS,LESIA, UPMC Univ Paris 06,Observ Paris,Sorbonne Paris Ci, F-92195 Meudon, France..
    Hasselmann, P.
    Sorbonne Univ, Univ Paris Diderot, PSL Res Univ,CNRS,LESIA, UPMC Univ Paris 06,Observ Paris,Sorbonne Paris Ci, F-92195 Meudon, France..
    Vincent, J. -B
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lamy, P.
    CNRS, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille 13, France.;Univ Aix Marseille, F-13388 Marseille 13, France..
    Rodrigo, R.
    Inst Nacl Tecn Aeroespacial, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    Keller, H. U.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Polish Acad Sci, Space Res Ctr, PL-00716 Warsaw, Poland..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Sorbonne Univ, Univ Paris Diderot, PSL Res Univ,CNRS,LESIA, UPMC Univ Paris 06,Observ Paris,Sorbonne Paris Ci, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Besse, S.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    Osserv Astron Padova, Ist Nazl Astrofis, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, Ist Foton & Nanotecnol, Unita Org Supporto, Padova Luxor, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, I-38123 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Deshapriya, J. D. P.
    Sorbonne Univ, Univ Paris Diderot, PSL Res Univ,CNRS,LESIA, UPMC Univ Paris 06,Observ Paris,Sorbonne Paris Ci, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, I-34014 Trieste, Italy..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S-N, Granada 18008, Spain..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S-N, Granada 18008, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lin, Z. -Yi
    Natl Cent Univ, Grad Inst Astron, Chungli 32054, Taiwan..
    Moreno, J. J. Lopez
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S-N, Granada 18008, Spain..
    Marchi, S.
    Southwest Res Inst, Virtual Inst, Solar Syst Explorat Res, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Naletto, G.
    CNR, Ist Foton & Nanotecnol, Unita Org Supporto, Padova Luxor, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy.;Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Oklay, N.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Preusker, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Scholten, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Surface changes on comet 67P/Churyumov-Gerasimenko suggest a more active past2017In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 355, no 6332, p. 1392-+Article in journal (Refereed)
    Abstract [en]

    The Rosetta spacecraft spent similar to 2 years orbiting comet 67P/Churyumov-Gerasimenko, most of it at distances that allowed surface characterization and monitoring at submeter scales. From December 2014 to June 2016, numerous localized changes were observed, which we attribute to cometary-specific weathering, erosion, and transient events driven by exposure to sunlight and other processes. While the localized changes suggest compositional or physical heterogeneity, their scale has not resulted in substantial alterations to the comet's landscape. This suggests that most of the major landforms were created early in the comet's current orbital configuration. They may even date from earlier if the comet had a larger volatile inventory, particularly of CO or CO2 ices, or contained amorphous ice, which could have triggered activity at greater distances from the Sun.

  • 20.
    El-Marry, M. R.
    et al.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Gracia-Berna, A.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studied Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Lee, J. -C
    Massironi, M.
    Univ Padua, Dipartimento Geosci, Via G Gradenigo 6, I-35131 Padua, Italy..
    Davidsson, B.
    Jet Prop Lab, M S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Marchi, S.
    Southwest Res Inst, Solar Syst Explorat Res Virtual Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Hviid, S. F.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Besse, S.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Sierks, H.
    Max Planck Inst Sonnensystemforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    INAF Osservatorio Astrono, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Rodrigo, R.
    Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland.;CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, Obs Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studied Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gremonese, G.
    INAF Osservatorio Astrono, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy..
    Dehei, S.
    Univ Padua, Dept Mech Engn, Via Venezia 1, I-35131 Padua, Italy..
    Guettler, C.
    Max Planck Inst Sonnensystemforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fornasier, S.
    Fulle, M.
    INAF Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, Italy..
    Giacomini, L.
    Groussin, O.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Ip, W. -H
    Natl Cent Univ, Grad Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Jorda, L.
    Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Knollenberg, J.
    Kovacs, G.
    Max Planck Inst Sonnensystemforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Kueppers, M.
    European Space Astron Ctr ESA, Sci Support Off, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Lazzarin, M.
    INAF Osservatorio Astrono, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Marschall, R.
    Marzari, F.
    INAF Osservatorio Astrono, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensystemforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pommerol, A.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Preusker, F.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensystemforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Regional surface morphology of comet 67P/Churyumov-Gerasimenko from Rosetta/OSIRIS images: The southern hemisphere2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 593, article id A110Article in journal (Refereed)
    Abstract [en]

    Aims. The OSIRIS camera on board the Rosetta spacecraft has been acquiring images of the comet 67P/Churyumov-Gerasimenko (67P)'s nucleus since August 2014. Starting in May 2015, the southern hemisphere gradually became illuminated and was imaged for the first time. Here we present the regional morphology of the southern hemisphere, which serves as a companion to an earlier paper that presented the regional morphology of the northern hemisphere. Methods. We used OSIRIS images that were acquired at orbits similar to 45-125 km from the center of the comet (corresponding to spatial resolutions of similar to 0.8 to 2.3 m/pixel) coupled with the use of digital terrain models to define the different regions on the surface, and identify structural boundaries accurately. Results. Seven regions have been defined in the southern hemisphere bringing the total number of defined regions on the surface of the nucleus to 26. These classifications are mainly based on morphological and/or topographic boundaries. The southern hemisphere shows a remarkable dichotomy with its northern counterpart mainly because of the absence of wide-scale smooth terrains, dust coatings and large unambiguous depressions. As a result, the southern hemisphere closely resembles previously identified consolidated regions. An assessment of the overall morphology of comet 67P suggests that the comet's two lobes show surface heterogeneities manifested in different physical/mechanical characteristics, possibly extending to local (i.e., within a single region) scales.

  • 21.
    Feller, C.
    et al.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Fornasier, S.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Hasselmann, P. H.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Barucci, A.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Preusker, F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Freder Joliot Curie, F-13388 Marseille, France..
    Pommerol, A.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Jost, B.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Poch, O.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    ElMaary, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Belskaya, I.
    Kharkov Natl Univ, Inst Astron, Sumska Str 35, UA-61022 Kharkov, Ukraine..
    Pajola, M.
    NASA, Ames Res Ctr, Moett Field, CA 94035 USA.;Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron Galileo Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Freder Joliot Curie, F-13388 Marseille, France..
    Koschny, D.
    ESA, European Space Res & Technol Ctr, Res & Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Poland..
    Rodrigo, R.
    CSIC, European Space Agcy, ESAC, Ctr Astrobiol,INTA, POB 78, Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Agarwal, J.
    A'Hearn, M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN, UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B. J. R.
    Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fulle, M.
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, Italy..
    Giquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Freder Joliot Curie, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Keller, H.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Ip, W. -H
    Knollenberg, J.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    ESAC, ESA, POB 78, E-28691 Madrid, Spain..
    Lara, M. L.
    Lazzarin, M.
    Leyrat, C.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Moreno, J. J. Lopez
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Marzari, F.
    Masoumzadeh, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Mottola, S.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Studies & Activ Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy.;CNR, IFN, UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Perna, D.
    Sorbonne Univ, UPMC Univ Paris 06, Univ Paris Diderot,CNRS, PSL Res Univ,LESIA,Observ Paris,Sorbanne Paris Ci, 5 Pl J Janssen, F-92195 Meudon, France..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Decimetre-scaled spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S287-S303Article in journal (Refereed)
    Abstract [en]

    We present the results of the photometric and spectrophotometric properties of the 67P/Churyumov-Gerasimenko nucleus derived with the Optical, Spectroscopic and Infrared Remote Imaging System instrument during the closest fly-by over the comet, which took place on 2015 February 14 at a distance of similar to 6 km from the surface. Several images covering the 0 degrees-33 degrees. phase angle range were acquired, and the spatial resolution achieved was 11 cm pixel(-1). The flown-by region is located on the big lobe of the comet, near the borders of the Ash, Apis and Imhotep regions. Our analysis shows that this region features local heterogeneities at the decimetre scale. We observed difference of reflectance up to 40 per cent between bright spots and sombre regions, and spectral slope variations up to 50 per cent. The spectral reddening effect observed globally on the comet surface by Fornasier et al. (2015) is also observed locally on this region, but with a less steep behaviour. We note that numerous metre-sized boulders, which exhibit a smaller opposition effect, also appear spectrally redder than their surroundings. In this region, we found no evidence linking observed bright spots to exposed water-ice-rich material. We fitted our data set using the Hapke 2008 photometric model. The region overflown is globally as dark as the whole nucleus (geometric albedo of 6.8 per cent) and it has a high porosity value in the uppermost layers (86 per cent). These results of the photometric analysis at a decimetre scale indicate that the photometric properties of the flown-by region are similar to those previously found for the whole nucleus.

  • 22.
    Fornasier, S.
    et al.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France.;Unix Paris Diderot, Sorbonne Paris Cite, F-75205 Paris 13, France..
    Hasselmann, P. H.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France.;Observ Nacl, Rio De Janeiro, Brazil..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France..
    Feller, C.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France.;Unix Paris Diderot, Sorbonne Paris Cite, F-75205 Paris 13, France..
    Besse, S.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Leyrat, C.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon Pricipal, France..
    Lara, L.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Scholten, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Reserch Ctr, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Cremonese, G.
    Osserv Astron Padova, INAF, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trent, UNITN, I-38100 Trento, Italy..
    Fulle, M.
    Osserv Astron Trieste, INAF, I-34143 Trieste, Italy..
    Groussin, O.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Matz, K. -D
    Michalik, H.
    Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, E-18080 Granada, Spain..
    Mottola, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Naetto, G.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Preusker, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Snodgrass, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany.;Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Vincent, J-B
    Spectrophotometric properties of the nucleus of comet 67P/Churyumov-Gerasimenko from the OSIRIS instrument onboard the ROSETTA spacecraft2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A30Article in journal (Refereed)
    Abstract [en]

    Context. The Rosetta mission of the European Space Agency has been orbiting the comet 67P/Churyumov-Gerasimenko (67P) since August 2014 and is now in its escort phase. A large complement of scientific experiments designed to complete the most detailed study of a comet ever attempted are onboard Rosetta. Aims. We present results for the photometric and spectrophotometric properties of the nucleus of 67P derived from the OSIRIS imaging system, which consists of a Wide Angle Camera (WAC) and a Narrow Angle Camera (NAC). The observations presented here were performed during July and the beginning of August 2014, during the approach phase, when OSIRIS was mapping the surface of the comet with several filters at different phase angles (1.3 degrees-54 degrees). The resolution reached up to 2.1 m/px. Methods. The OSIRIS images were processed with the OSIRIS standard pipeline, then converted into I/F. radiance factors and corrected for the illumination conditions at each pixel using the Lommel-Seeliger disk law. Color cubes of the surface were produced by stacking registered and illumination-corrected images. Furthermore, photometric analysis was performed both on disk-averaged photometry in several filters and on disk-resolved images acquired with the NAC orange filter, centered at 649 ran, using Hapke modeling. Results. The disk-averaged phase function of the nucleus of 67P shows a strong opposition surge with a G parameter value of -0.13 +/- 0.01 in the HG system formalism and an absolute magnitude H-v(1, 1, 0) = 15.74 +/- 0.02 mag. The integrated spectrophotometry in 20 filters covering the 250-1000 nm wavelength range shows a red spectral behavior, without clear absorption bands except for a potential absorption centered at similar to 290 rim that is possibly due to SO2 ice. The nucleus shows strong phase reddening, with disk-averaged spectral slopes increasing from 11%/( 100 nm) to 16%/(100 nm) in the 1.3 degrees-54 degrees phase angle range. The geometric albedo of the comet is 6.5 +/- 0.2% at 649 nm, with local variations of up to similar to 16% in the Hapi region. From the disk-resolved images we computed the spectral slope together with local spectrophotometry and identified three distinct groups of regions (blue, moderately red, and red). The Hapi region is the brightest, the bluest in term of spectral slope, and the most active surface on the comet. Local spectrophotometry shows an enhancement of the flux in the 700-750 nm that is associated with coma emissions.

  • 23.
    Fornasier, S.
    et al.
    Sorbonne Univ, UPMC Univ Paris 06,Sorbonne Paris Cite, Univ Paris Diderot,PSL Res Univ, CNRS,Observ Paris,LESIA, 5 Pl J Janssen, F-92125 Meudon, France..
    Mottola, S.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany..
    Keller, H. U.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Barucci, M. A.
    Sorbonne Univ, UPMC Univ Paris 06,Sorbonne Paris Cite, Univ Paris Diderot,PSL Res Univ, CNRS,Observ Paris,LESIA, 5 Pl J Janssen, F-92125 Meudon, France..
    Davidsson, B.
    Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Feller, C.
    Sorbonne Univ, UPMC Univ Paris 06,Sorbonne Paris Cite, Univ Paris Diderot,PSL Res Univ, CNRS,Observ Paris,LESIA, 5 Pl J Janssen, F-92125 Meudon, France..
    Deshapriya, J. D. P.
    Sorbonne Univ, UPMC Univ Paris 06,Sorbonne Paris Cite, Univ Paris Diderot,PSL Res Univ, CNRS,Observ Paris,LESIA, 5 Pl J Janssen, F-92125 Meudon, France..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo dellOsservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Univ Aix Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rodrigo, R.
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S N, Granada 18008, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Res & Technol Centre ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Polish Acad Sci, Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    A'Hearn, M.
    Univ Maryland, Dept Phys & Astron, College Pk, MD 20742 USA..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dept Phys & Astron, Vicolo dellOsservatorio 3, I-35122 Padua, Italy..
    Besse, S.
    European Space Astron Ctr ESA, Operat Dept, POB 78, F-28691 Madrid, Spain..
    Cremonese, G.
    INAF, Osservatorio Via Venezia 1, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Mech Engn, Via Venezia 1, I-35131 Trento, Italy..
    De Cecco, M.
    Univ Trent, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S N, Granada 18008, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Knollenberg, J.
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.;Budapest Univ Technol & Econ, Budapest, Hungary..
    Kramm, R.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kuehrt, E.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, F-28691 Madrid, Spain..
    Lara, M. L.
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S N, Granada 18008, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo dellOsservatorio 3, I-35122 Padua, Italy..
    Moreno, J. J. Lopez
    Inst Astrofis Andalucia CSIC, C Glorieta Astron S N, Granada 18008, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo dellOsservatorio 3, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, Via G Gradenigo 6, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS, Via Venezia 15, I-35131 Padua, Italy..
    Naletto, G.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS, Via Venezia 15, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS, Via Venezia 15, I-35131 Padua, Italy.;NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Pommerol, A.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Preusker, F.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany..
    Scholten, F.
    Inst Planetenforschung Asteroiden & Kometen, Deutsches Zentrum Luft & Raumfahrt DLR, Rutherfordstrafle 2, D-12489 Berlin, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, H-1121 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Rosetta's comet 67P/Churyumov-Gerasimenko sheds its dusty mantle to reveal its icy nature2016In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 354, no 6319, p. 1566-1570Article in journal (Refereed)
    Abstract [en]

    The Rosetta spacecraft has investigated comet 67P/Churyumov-Gerasimenko from large heliocentric distances to its perihelion passage and beyond. We trace the seasonal and diurnal evolution of the colors of the 67P nucleus, finding changes driven by sublimation and recondensation of water ice. The whole nucleus became relatively bluer near perihelion, as increasing activity removed the surface dust, implying that water ice is widespread underneath the surface. We identified large (1500 square meters) ice-rich patches appearing and then vanishing in about 10 days, indicating small-scale heterogeneities on the nucleus. Thin frosts sublimating in a few minutes are observed close to receding shadows, and rapid variations in color are seen on extended areas close to the terminator. These cyclic processes are widespread and lead to continuously, slightly varying surface properties.

  • 24.
    Fouchard, M.
    et al.
    Univ Lille 1, LAL, F-59000 Lille, France.;Inst Mecan Celeste & Calcul Ephermerides, 77 Av Denfert Rochereau, F-75014 Paris, France.;Observ Lille, 1 Impasse Observ, F-59000 Lille, France..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland.
    Froeschle, Ch.
    CNRS, UNSA, UMR 6202, Observ Cote Azur, Bd Observ,BP 4229, F-06304 Nice 4, France..
    Valsecchi, G. B.
    INAF, IAPS, Via Fosso Cavaliere 100, I-00133 Rome, Italy.;CNR, IFAC, Via Madonna Piano 10, I-50019 Sesto Fiorentino, FI, Italy..
    Distribution of long-period comets: comparison between simulations and observations2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 604, article id A24Article in journal (Refereed)
    Abstract [en]

    Aims: This paper is devoted to a comparison between observations and simulations of the so-called Oort spike formed by the "new" observable long-period comets.

    Methods: The synthetic distributions of observable comets come from the propagation of a huge sample of objects during the age of the solar system that were initially in a proto-Oort cloud, which was flattened around the ecliptic and had perihelia in the region of Uranus and Neptune. For the known new long-period comets, two samples were used, one that is assumed to be complete, and the comets of the other exclusively come from the Warsaw catalog of comets. The original orbital energy of the comets in this catalog is more reliable.

    Results: Considering comets with a perihelion distance smaller than 4 AU, for which one of our samples of known comets can be assumed to be complete, the comparison shows small but significant differences in the orbital energy distribution and in the proportion of retrograde comets. When we extend the limiting perihelion distance to 10 AU, the observed samples are obviously strongly incomplete. The synthetic distribution shows that the number of observable comets per year and per perihelion distance unit is proportional to q(1.09) for q < 4 AU and proportional to q(2.13) for 6 < q < 10 AU. The increase for q > 6 AU comes from comets that were already within the Jupiter-Saturn barrier (q < 15 AU) at their previous perihelion passage (which we call creepers and Kaib and Quinn creepers), with original semi-major axes generally smaller than 20 000 AU.

    Conclusions: To explain the small but significant differences between our synthetic sample and the known comets for a perihelion distance smaller than 4 AU, different hypotheses are proposed: a still erroneous value of the original orbital energy in the observed sample, a higher density of low-mass stars in the actual solar neighborhood, a ninth planet, and obviously the initial population of objects from which the synthetic distributions are derived.

  • 25.
    Fouchard, M.
    et al.
    Univ Lille, UPMC Univ Paris 06, Sorbonne Univ, PSL Res Univ,LAL IMCCE,Observ Paris,CNRS, 1 Impasse Observ, F-59000 Lille, France..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Froeschle, Ch.
    Observ Cote Azur, UMR 7293, Blvd Observ,BP 4229, F-06304 Nice 4, France..
    Valsecchi, G. B.
    IAPS INAF, Via Fosso Cavaliere 100, I-00133 Rome, Italy.;IFAC CNR, Via Madonna del Piano 10, I-50019 Sesto Fiorentino, FI, Italy..
    On the present shape of the Oort cloud and the flux of "new" comets2017In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 292, p. 218-233Article in journal (Refereed)
    Abstract [en]

    Long term evolution of an initial set of 10(7) Oort cloud comets is performed for the age of the solar system taking into account the action of passing stars using 10 different sequences of stellar encounters, Galactic tides and the gravity of the giant planets. The initial conditions refer to a disk-shaped Oort cloud precursor, concentrated toward the ecliptic with perihelia in the region of Uranus and Neptune. Our results show that the shape of the Oort cloud quickly reach a kind of steady state beyond a semi-major axis greater than about 2000 AU (this threshold depending on the evolution time-span), with a Boltzmann distribution of the orbital energy. The stars act in an opposite way to what was found in previous papers, that is they emptied an initial Tidal Active Zone that is overfilled with respect to the isotropic case. Consequently, the inclusion of stellar perturbations strongly affect the shape of the Oort spike. On the contrary, the Oort spike shape appears to be poorly dependent on the stellar sequences used, whereas the total flux of observable comets and the proportion of retrograde comets for the inner part of the spike are significantly dependent of it. Then it has been highlighted that the total flux, the shape of the Oort spike and the shape of the final Oort cloud are almost independent of the initial distribution of orbital energy considered.

  • 26. Fouchard, M.
    et al.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Froeschle, Ch
    Valsecchi, G. B.
    Planetary perturbations for Oort Cloud comets. I. Distributions and dynamics2013In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 222, no 1, p. 20-31Article in journal (Refereed)
    Abstract [en]

    This paper is the first in a series, where we aim to model the injection of comets from the Oort Cloud so well that the shape of the energy distribution of long-period comets (i.e., the distribution of reciprocal semi-major axis) together with the observed rate of perihelion passages can be used to make serious inferences about the population size and energy distribution of the cloud. Here we explore the energy perturbations caused by the giant planets on long-period comets with perihelia inside or near the planetary system. We use a simplified dynamical model to integrate such perturbations for large samples of fictitious comets and analyse the statistics of the outcomes. After demonstrating the sensitivity of derived parameters to the sample size, when close encounters are involved, we derive a map of the RMS energy perturbation as a function of perihelion distance (q) and the cosine of the inclination (i), which compares well with the results of previous papers. We perform a critical analysis of the loss cone concept by deriving the "opacity" (chance of leaving the Oort spike by planetary perturbations per perihelion passage) as a function of q and cos i, concluding that the often made assumption of full opacity for q < 15 AU is seriously in error. While such a conclusion may also have been drawn from earlier studies, we provide the first full, quantitative picture. Moreover, we make a preliminary investigation of the long-term evolution of long-period comet orbits under the influence of planetary perturbations, neglecting the external effects of Galactic tides and stellar encounters. This allows us to make predictions about the production of decoupled objects like Halley-type comets and Centaurs from the injection of Oort Cloud comets, as well as of a related population of transneptunians deriving from the Oort Cloud with perihelia well detached from the planets.

  • 27. Fouchard, M.
    et al.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Froeschle, Ch.
    Valsecchi, G. B.
    Planetary perturbations for Oort cloud comets: II. Implications for the origin of observable comets2014In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 231, p. 110-121Article in journal (Refereed)
    Abstract [en]

    We present Monte Carlo simulations of the dynamical history of the Oort cloud, where in addition to the main external perturbers (Galactic tides and stellar encounters) we include, as done in a companion paper (Fouchard, M., Rickman, H., Froeschle, Ch., Valsecchi, G.B. [2013b] Icarus, in press), the planetary perturbations experienced each time the comets penetrate to within 50 AU of the Sun. Each simulation involves an initial sample of four million comets and extends over a maximum of 5 Gyr. For better understanding of the outcomes, we supplement the full dynamical model by others, where one or more of the effects are left out. We concentrate on the production of observable comets, reaching for the first time a perihelion within 5 AU of the Sun. We distinguish between four categories, depending on whether the comet jumps across, or creeps through, the Jupiter-Saturn barrier (perihelion distances between 5 and 15 AU), and whether the orbit leading to the observable perihelion is preceded by a major planetary perturbation or not. For reasons explained in the paper, we call the strongly perturbed comets "Kaib-Quinn comets". We thus derive a synthetic picture of the Oort spike, from which we draw two main conclusions regarding the full dynamical model. One is that 2/3 of the observable comets are injected with the aid of a planetary perturbation at the previous perihelion passage, and about half of the observable comets are of the Kaib-Quinn type. The other is that the creepers dominate over the jumpers. Due to this fact, the spike peaks at only 31000 AU, and the majority of new comets have semi-major axes less than this value. The creepers show a clear preference for retrograde orbits as a consequence of the need to avoid untimely, planetary ejection before becoming observable. Thus, the new comets should have a 60/40 preference for retrograde against prograde orbits in apparent conflict with observations. However, both these and other results depend on our model assumptions regarding the initial structure of the Oort cloud, which is isotropic in shape and has a relatively steep energy distribution. We also find that they depend on the details of the past history of external perturbations including GMC encounters, and we provide special discussions of those issues.

  • 28. Fouchard, M.
    et al.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Froeschle, Ch.
    Valsecchi, G. B.
    Planetary perturbations for Oort cloud comets: III. Evolution of the cloud and production of centaurs and Halley type comets2014In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 231, p. 99-109Article in journal (Refereed)
    Abstract [en]

    We present Monte Carlo simulations of the dynamical history of the Oort cloud, where in addition to the main external perturbers (Galactic tides and stellar encounters) we include, as done in a companion paper (Fouchard, M., Rickman, H., Froeschle, Ch., Valsecchi, G.B. [2013b] Icarus, in press), the planetary perturbations experienced each time the comets penetrate to within 50 AU of the Sun. Each simulation involves an initial sample of four million comets and extends over a maximum of 5 Gyr. For better understanding of the outcomes, we supplement the full dynamical model by others, where one or more of the effects are left out. In the companion paper we studied in detail how observable comets are injected from the Oort cloud, when account is taken of the planetary perturbations. In the present paper we concentrate on how the cloud may evolve in the long term and also on the production of decoupled comets, which evolve into semi-major axes less than 1000 AU. Concerning the long-term evolution, we find that the largest stellar perturbations that may statistically be expected during the age of the Solar System induce a large scale migration of comets within the cloud. Thus, comets leave the inner parts, but the losses from the outer parts are even larger, so at the end of our simulations the Oort cloud is more centrally condensed than at the beginning. The decoupled comets, which form a source of centaurs and Halley type comets (roughly in the proportions of 70% and 30%, respectively), are mainly produced by planetary perturbations, Jupiter and Saturn being the most efficient. This effect is dependent on synergies with the Galactic tide and stellar encounters, bringing the perihelia of Oort cloud comets into the planetary region. The star-planet synergy has a large contribution due to the strong encounters that produce major comet showers. However, outside these showers a large majority of decouplings may be attributed to the tide-planet synergy.

  • 29. Fouchard, M.
    et al.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Froeschle, Ch.
    Valsecchi, G. B.
    The last revolution of new comets: the role of stars and their detectability2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 535, p. A86-Article in journal (Refereed)
    Abstract [en]

    Context. This work is a follow-up of a previous study, where we simulated the dynamical evolution of the Oort Cloud over 5 Gyr with special attention to the injection of comets into observable orbits.

    Aims. We wish to clarify how comet injection operates with two types of perturbers: Galactic tides and passing stars. We illustrate why attempts to identify the stars that might have played an important role in injecting the observed new Oort Cloud comets are as yet unlikely to succeed, and investigate how large an improvement can be expected from the Gaia mission.

    Methods. We simulate a 5 Gyr time span, concentrating on the injections found during the last 3 Gyr by extracting detailed information about the last revolution of the injected comets. We analyse the contributions of both the Galactic tides and the stars separately, and assess their importance as a function of the semi-major axis of the comets. We also compute the distances and motions of the perturbing stars at the time the comets reach their perihelia and thus estimate their observability.

    Results. By studying more than 20 000 injected comets, we determine how the likelihood of tidal and stellar injections varies with the semi-major axis. We establish the range of semi-major axis for which a real-time synergy between stellar and tidal perturbations is important. We find how many perturbing stars could be identified using HIPPARCOS and Gaia data, and how the dynamics of injections would change, if only the observable stars were acting.

    Conclusions. The number of injected comets peaks at a semi-major axis (a) of about 33 000 AU but the comets spread over a wide range around this value. The tides are unable to inject any comets at a < 23 000 AU but would be able to inject almost all of them at a > 50 000 AU. The real-time synergy is found to extend between a similar to 15 000 AU and a similar to 45 000 AU and to be the main contributor at a similar to 25 000 AU. Stellar perturbations make important contributions at all semi-major axes. On the basis of HIPPARCOS data, only a minority of the stars that may contribute to comet injections are detectable, since most stars have escaped to distances beyond the HIPPARCOS detection limit. For Gaia, on the other hand, a large majority of the perturbing stars will be both identifiable and measurable.

  • 30. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Breiter, Sławomir
    Ratajczak, Roman
    Valsecchi, Giovanni B.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: II. Modelling the Galactic Tide2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 273-296Chapter in book (Other academic)
  • 31. Fouchard, Marc
    et al.
    Froeschlé, Christiane
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics. Astronomiska Observatoriet. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, Theoretical Astrophysics.
    Valsecchi, Giovanni B.
    Methods for the Study of the Dynamics of the Oort Cloud Comets: I: Modelling the Stellar Perturbations2007In: Topics in Gravitational Dynamics: Solar, Extra-Solar and Galactic Systems / [ed] Daniel Benest, Claude Froeschle and Elena Lega, Berlin, Heidelberg: Springer-Verlag , 2007, p. 257-272Chapter in book (Other academic)
  • 32.
    Fulle, M.
    et al.
    INAF Osservatorio Astron, I-34143 Trieste, Italy..
    Ivanovski, S. L.
    INAF Ist Astrofis & Planetol Spaziali, Area Ric Tor Vergata, I-00133 Rome, Italy..
    Bertini, I.
    Univ Padua, CISAS, I-35100 Padua, Italy..
    Gutierrez, P.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lara, L.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Zakharov, V.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Della Corte, V.
    INAF Ist Astrofis & Planetol Spaziali, Area Ric Tor Vergata, I-00133 Rome, Italy..
    Rotundi, A.
    INAF Ist Astrofis & Planetol Spaziali, Area Ric Tor Vergata, I-00133 Rome, Italy.;Univ Napoli Parthenope, Dip Sci & Tecnol, I-80143 Naples, Italy..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France.;Aix Marseille Univ, F-13388 Marseille, France..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid 28691, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Groussin, O.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France.;Aix Marseille Univ, F-13388 Marseille, France..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France.;Aix Marseille Univ, F-13388 Marseille, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, Madrid 28692, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez-Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Marzari, F.
    Univ Padua, Dept Phys, I-35131 Padua, Italy..
    Michalik, H.
    Inst Datentech & Konununikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, CISAS, I-35100 Padua, Italy.;Univ Padua, Dept Mech Engn, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Sabau, L.
    Inst Nacl Tecn Aeroespacial, Madrid 28850, Spain..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Wenzel, K. -P
    Rotating dust particles in the coma of comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A14Article in journal (Refereed)
    Abstract [en]

    Context. During September and October 2014, the OSIRIS cameras onboard the ESA Rosetta mission detected millions of single particles. Many of these dust particles appear as long tracks (due to both the dust proper motion and the spacecraft motion during the exposure time) with a clear brightness periodicity. Aims. We interpret the observed periodic features as a rotational and translational motion of aspherical dust grains. Methods. By counting the peaks of each track, we obtained statistics of a rotation frequency. We compared these results with the rotational frequency predicted by a model of aspherical dust grain dynamics in a model gas flow. By testing many possible sets of physical conditions and grain characteristics, we constrained the rotational properties of dust grains. Results. We analyzed on the motion of rotating aspherical dust grains with different cross sections in flow conditions corresponding to the coma of 67P/Churyumov-Gerasimenko qualitatively and quantitatively. Based on the OSIRIS observations, we constrain the possible physical parameters of the grains.

  • 33.
    Fulle, M.
    et al.
    INAF Osservatorio Astron, Via Tiepolo 11, I-34143 Trieste, Italy..
    Marzari, F.
    Univ Padua, Dept Phys, I-35131 Padua, Italy..
    Della Corte, V.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Fornasier, S.
    Univ Paris 06, Univ Paris 04, Univ Paris Diderot, Observ Paris,LESIA,Observ Paris,PSL Res Univ,CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Rotundi, A.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy.;Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseilles, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, E-28691 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, ESA ESTEC, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Accolla, M.
    INAF Osservatorio Astrofis Catania, Via Santa Sofia 78, I-95123 Catania, Italy..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Altobelli, N.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain..
    Barucci, M. A.
    Univ Paris 06, Univ Paris 04, Univ Paris Diderot, Observ Paris,LESIA,Observ Paris,PSL Res Univ,CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, CISAS, Via Venezia 15, I-35100 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Bussoletti, E.
    Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Colangeli, L.
    European Space Agcy, ESA ESTEC, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Cosi, M.
    Selex ES, Via A Einstein 35, I-50013 Campi Bisenzio, FI, Italy..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Crifo, J. -F
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Mech Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trent, UNITN, Via Mesiano 77, I-38100 Trento, Italy..
    Esposito, F.
    INAF Osservatorio Astron Capodimonte, Salita Moiariello 16, I-80133 Naples, Italy..
    Ferrari, M.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Giovane, F.
    Virginia Polytech Inst & State Univ, Blacksburg, VA 24061 USA..
    Gustafson, B.
    Univ Florida, Gainesville, FL 32611 USA..
    Green, S. F.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Groussin, O.
    CNRS, UMR 7326, Lab Astrophys Marseilles, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Gruen, E.
    Max Planck Inst Kernphys, Saupfercheckweg 1, D-69117 Heidelberg, Germany..
    Gutierrez, P.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Herranz, M. L.
    INAF Osservatorio Astrofis Catania, Via Santa Sofia 78, I-95123 Catania, Italy..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W.
    Natl Cent Univ, Inst Space Sci, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Ivanovski, S. L.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Jeronimo, J. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Jorda, L.
    CNRS, UMR 7326, Lab Astrophys Marseilles, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, R.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kueppers, M.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain..
    Lara, L.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Leese, M. R.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Lopez-Jimenez, A. C.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Lucarelli, F.
    Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Epifani, E. Mazzotta
    INAF Osservatorio Astron Roma, Via Frascati 33, Rome, Italy..
    McDonnell, J. A. M.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England.;Univ Kent, Sch Phys Sci, Canterbury CT2 7NZ, Kent, England.;UnispaceKent, Canterbury CT2 8EF, Kent, England..
    Mennella, V.
    INAF Osservatorio Astron Capodimonte, Salita Moiariello 16, I-80133 Naples, Italy..
    Molina, A.
    Univ Granada, Fac Ciencias, Dept Fis Aplicada, Avda Severo Ochoa S-N, E-18071 Granada, Spain..
    Morales, R.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Mottola, S.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, CISAS, Via Venezia 15, I-35100 Padua, Italy.;Univ Padua, Dept Mech Engn, Via Venezia 1, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Ortiz, J. L.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Palomba, E.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Palumbo, P.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy.;Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Perrin, J. -M
    Rietmeijer, F. J. M.
    1 Univ New Mexico, Dept Earth & Planetary Sci, MSC03 2040, Albuquerque, NM 87131 USA..
    Rodriguez, J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Sordini, R.
    INAF Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Weissman, P.
    Planetary Sci Inst, 1700 East Ft Lowell,Suite 106, Tucson, AZ 85719 USA..
    Wenzel, K. -P
    Zakharov, V.
    Univ Paris 06, Univ Paris 04, Univ Paris Diderot, Observ Paris,LESIA,Observ Paris,PSL Res Univ,CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
    Zarnecki, J. C.
    Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland.;Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Evolution Of The Dust Size Distribution Of Comet 67P/Churyumov-Gerasimenko From 2.2 Au To Perihelion2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 821, no 1, article id 19Article in journal (Refereed)
    Abstract [en]

    The Rosetta probe, orbiting Jupiter-family comet 67P/Churyumov-Gerasimenko, has been detecting individual dust particles of mass larger than 10(-10) kg by means of the GIADA dust collector and the OSIRIS Wide Angle Camera and Narrow Angle Camera since 2014 August and will continue until 2016 September. Detections of single dust particles allow us to estimate the anisotropic dust flux from 67P, infer the dust loss rate and size distribution at the surface of the sunlit nucleus, and see whether the dust size distribution of 67P evolves in time. The velocity of the Rosetta orbiter, relative to 67P, is much lower than the dust velocity measured by GIADA, thus dust counts when GIADA is nadir-pointing will directly provide the dust flux. In OSIRIS observations, the dust flux is derived from the measurement of the dust space density close to the spacecraft. Under the assumption of radial expansion of the dust, observations in the nadir direction provide the distance of the particles by measuring their trail length, with a parallax baseline determined by the motion of the spacecraft. The dust size distribution at sizes > 1 mm observed by OSIRIS is consistent with a differential power index of -4, which was derived from models of 67P's trail. At sizes <1 mm, the size distribution observed by GIADA shows a strong time evolution, with a differential power index drifting from -2 beyond 2 au to -3.7 at perihelion, in agreement with the evolution derived from coma and tail models based on ground-based data. The refractory-to-water mass ratio of the nucleus is close to six during the entire inbound orbit and at perihelion.

  • 34.
    Fulle, Marco
    et al.
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34143 Trieste, Italy.
    Bertini, I.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Ossevatorio 3, I-35122 Padua, Italy.
    Della Corte, V.
    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy;Univ Napoli Parthenope, Dip Sci & Technol, CDN IC4, I-80143 Naples, Italy.
    Guttler, C.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Ivanovski, S.
    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy;Univ Napoli Parthenope, Dip Sci & Technol, CDN IC4, I-80143 Naples, Italy.
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Ossevatorio 3, I-35122 Padua, Italy.
    Lasue, J.
    Uni Tolouse, UPS OMP, IRAP, I-31400 Toulouse, France;CNRS, IRAP, 9 Ave Colonel Roche,BP 44346, E-31028 Toulouse 4, France.
    Levasseur-Regourd, A. C.
    Sorbonne Univ, UVSQ UPSay, CNRS INSU, LATMOS IPSL, BC 102,Campus UPMC,4 Pl Jussieu, F-75005 Paris, France.
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Ossevatorio 3, I-35122 Padua, Italy.
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Mottola, S.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Naletto, G.
    Univ Padua, Dept Phys & Astron G Galilei, Via Marzolo 8, I-35131 Padua, Italy;Univ Padua, Ctr Studies & Act Space, CISAS, Via Venezia 15, I-35131 Padua, Italy;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.
    Palumbo, P.
    Univ Napoli Parthenope, Dip Sci & Technol, CDN IC4, I-80143 Naples, Italy.
    Rinaldi, G.
    INAF, Ist Astrofis & Planetol Spaziali, Via Fosso del Cavaliere 100, I-00133 Rome, Italy;Univ Napoli Parthenope, Dip Sci & Technol, CDN IC4, I-80143 Naples, Italy.
    Rotundi, A.
    Univ Napoli Parthenope, Dip Sci & Technol, CDN IC4, I-80143 Naples, Italy.
    Sierks, H.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Ossevatorio 3, I-35122 Padua, Italy.
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille 13, France;Aix Marseille Univ, F-13388 Marseille 13, France.
    Rodrigo, R.
    CSIC, Ctr Astrobiol, INTA, E-28850 Madrid, Spain;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland.
    Koschny, D.
    ESA, Sci Support Off, European Space Res & Technol Ctr, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland.
    Barucci, M. A.
    Univ Paris 06, UPMC, Sorbonne Univ,Observ Paris, Sorbonne Paris Cite,Univ Paris Diderot,PSL Res Un, 5 Pl Jules Janssen, F-11111 Paris, France.
    Bertaux, J. -L
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.
    Davidsson, B.
    Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy.
    De Cecco, M.
    Univ Trento, Fac Engn, Via Mesiano 77, I-38121 Trento, Italy.
    Deller, J.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Fornasier, S.
    Univ Paris 06, UPMC, Sorbonne Univ,Observ Paris, Sorbonne Paris Cite,Univ Paris Diderot,PSL Res Un, 5 Pl Jules Janssen, F-11111 Paris, France.
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Hviid, H. S.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Ip, W. H.
    Natl Cent Univ, Grad Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan;Macau Univ Sci & Technol, Space Sci Inst, Ave Wal Long, Taipa, Macao, Peoples R China.
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France.
    Keller, H. U.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Mendelssohnstr 3, D-38106 Braunschweig, Germany.
    Knollenberg, J.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kramm, J. R.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kuhrt, E.
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kuppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, E-28691 Madrid, Spain.
    Lara, M. L.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Ossevatorio 3, I-35122 Padua, Italy.
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Shi, X.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland.
    Tubiana, C.
    Max Planck Inst Stromungsforsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    The phase function and density of the dust observed at comet 67P/Churyumov-Gerasimenko2018In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 476, no 2, p. 2835-2839Article in journal (Refereed)
    Abstract [en]

    The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observed close to Rosetta by OSIRIS, occurring about every hour, consistent with the fragmentation on impact with Rosetta of parent particles, whose flux agrees with the dust flux observed by GIADA. OSIRIS also measured the antisunward acceleration of the fragments, thus providing the first direct measurement of the solar radiation force acting on the dust fragments and thus of their bulk density, excluding any measurable rocket effect by the ice sublimation from the dust. The obtained particle density distribution has a peak matching the bulk density of most COSIMA particles, and represents a subset of the density distribution measured by GIADA. This implies a bias in the elemental abundances measured by COSIMA, which thus are consistent with the 67P dust mass fractions inferred by GIADA, i.e. (38 +/- 8) per cent of hydrocarbons versus the (62 +/- 8) per cent of sulphides and silicates.

  • 35.
    Giacomini, L.
    et al.
    Univ Padua, Dipartimento Geosci, Via G Gradenigo 6, I-35131 Padua, Italy..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, Via G Gradenigo 6, I-35131 Padua, Italy..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Penasa, L.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Pajola, M.
    NASA Ames Res Ctr, Moffett Field, CA 94035 USA..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Lowry, S. C.
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NZ, Kent, England..
    Barbieri, C.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vic Osservatorio 5, I-35122 Padua, Italy..
    Ferri, F.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Bertini, I.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    La Forgia, F.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lazzarin, M.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Marzari, F.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Sierks, H.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Lamy, P. L.
    CNRS, UMR 7236, Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Poland.
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, UPMC, LESIA Observ Paris,CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Besse, S.
    European Space Res & Technol Ctr ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, UPMC, LESIA Observ Paris,CNRS, 5 Pl J Janssen, F-92195 Meudon, France.;Univ Paris Diderot, Sorbonne Paris Cite, 4 Rue Elsa Morante, F-75205 Paris 13, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    CNRS, UMR 7236, Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Inst Planeten Forsch, Deutsch Zentrum Luft & Raumfahrt, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    CNRS, UMR 7236, Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Knollenberg, J.
    Inst Planeten Forsch, Deutsch Zentrum Luft & Raumfahrt, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Inst Planeten Forsch, Deutsch Zentrum Luft & Raumfahrt, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, E-28691 Madrid, Spain..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, E-18008 Granada, Spain..
    Lopez Moreno, J. J.
    Inst Astrofis Andalucia CSIC, E-18008 Granada, Spain..
    Magrin, S.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Michalik, H.
    TU Braunschweig, Inst Datentech & Kommunikat Netze, Hans Sommer Str 66, D-38106 Braunschweig, Germany..
    Oklay, N.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pommerol, A.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Preusker, F.
    Inst Planeten Forsch, Deutsch Zentrum Luft & Raumfahrt, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    Inst Planeten Forsch, Deutsch Zentrum Luft & Raumfahrt, Rutherfordstr 2, D-12489 Berlin, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Geologic mapping of the Comet 67P/Churyumov-Gerasimenko's Northern hemisphere2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S352-S369Article in journal (Refereed)
    Abstract [en]

    The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS), the scientific imaging system onboard the Rosetta mission, has been acquiring images of the nucleus of the comet 67P/Churyumov-Gerasimenko since 2014 August with a resolution which allows a detailed analysis of its surface. Indeed, data reveal a complex surface morphology which is likely the expression of different processes which occurred at different times on the cometary nucleus. In order to characterize these different morphologies and better understand their distribution, we performed a geologic mapping of comet's 67P Northern hemisphere in which features have been distinguished based on their morphological, textural and stratigraphic characteristics. For this purpose, we used narrow-angle camera images acquired in 2014 August and September with a spatial scale ranging from 1.2 to 2.4 m pixel(-1). Several different geologic units have been identified on the basis of their different surface textures, granulometry and morphology. Some of these units are distinctive and localized, whereas others are more common and distributed all over the Northern hemisphere. Moreover, different types of linear features have been distinguished on the basis of their morphology. Some of these lineaments have never been observed before on a comet and can offer important clues on the internal structures of the nucleus itself. The geologic mapping results presented here will allow us to better understand the processes which affected the nucleus' surface and thus the origin and evolutionary history of comet 67P/Churyumov-Gerasimenko.

  • 36.
    Gicquel, A.
    et al.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Li, Z. -Y
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    ESAC, European Space Agcy, CSIC, Ctr Astrobiol,INTA, POB 78, E-28691 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Poland.
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Barucci, M. A.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon Pricipal, France..
    Bertaux, J. -L
    Besse, S.
    European Space Agcy, Res & Sci Support Dept, NL-2201 AZ Noordwijk, Netherlands..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    De Cecco, M.
    Univ Trento, Via Sommarive 9, I-38123 Trento, Italy..
    Frattin, E.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, UPMC Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon Pricipal, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34143 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Gutierrez-Marquez, P.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hoefner, S.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.;TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hu, X.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.;Budapest Univ Technol & Econ, Dept Mechatron Opt & Engn Informat, Muegyet Rkp 3, H-1111 Budapest, Hungary..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kueppers, M.
    ESAC, ESA, POB 78, E-28691 Villanueva De La Canada, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Lowry, S.
    Univ Kent, Sch Phys Sci, Ctr Astrophys & Planetary Sci, Canterbury CT2 7NH, Kent, England..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Masoumzadeh, N.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Massironi, M.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy..
    Moreno, F.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Mottola, S.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy..
    Pommerol, A.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Preusker, F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Toth, I.
    Aix Marseille Univ, Lab Astrophys Marseille, UMR 7326, F-13388 Marseille, France.;Observ Hungarian Acad Sci, POB 67, H-1525 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S57-S66Article in journal (Refereed)
    Abstract [en]

    Beginning in 2014 March, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet's dust jets. We analysed the dust monitoring observations shortly after the southern vernal equinox on 2015 May 30 and 31 with the WAC at the heliocentric distance R-h = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this paper was that through the sublimation of the aggregates of dirty grains (radius a between 5 and 50 mu m) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data, we needed to inject a number of aggregates between 8.5 x 10(13) and 8.5 x 10(10) for a = 5 and 50 mu m, respectively, or an initial mass of H2O ice around 22 kg.

  • 37.
    Groussin, O.
    et al.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Auger, A. -T
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Gaske, R.
    Planetary Sci Inst, Tucson, AZ 85721 USA..
    Capanna, C.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Scholten, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Preusker, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Lamy, P.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Hviid, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Keller, U.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Huettig, C.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid 28691, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali, Giuseppe Colombo CISAS, I-35131 Padua, Italy..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Cremonese, G.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Ip, W. -H
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Kramm, J. -R
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lopez Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Marchi, S.
    SW Res Inst, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali, Giuseppe Colombo CISAS, I-35131 Padua, Italy.;Osserv Astron Padova, INAF, I-35122 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali, Giuseppe Colombo CISAS, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali, Giuseppe Colombo CISAS, I-35131 Padua, Italy..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Toth, I.
    Konkoly Observ Budapest, H-1525 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Gravitational slopes, geomorphology, and material strengths of the nucleus of comet 67P/Churyumov-Gerasimenko from OSIRIS observations2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A32Article in journal (Refereed)
    Abstract [en]

    Aims. We study the link between gravitational slopes and the surface morphology on the nucleus of comet 67P/Churyumov-Gerasimenko and provide constraints on the mechanical properties of the cometary material (tensile, shear, and compressive strengths). Methods. We computed the gravitational slopes for five regions on the nucleus that are representative of the different morphologies observed on the surface (Imhotep, Ash, Seth, Hathor, and Agilkia), using two shape models computed from OSIRIS images by the stereo-photoclinometry (SPC) and stereo-photogrammetry (SPG) techniques. We estimated the tensile, shear, and compressive strengths using different surface morphologies (overhangs, collapsed structures, boulders, cliffs, and Philae's footprint) and mechanical considerations. Results. The different regions show a similar general pattern in terms of the relation between gravitational slopes and terrain morphology: i) low-slope terrains (0-20 degrees) are covered by a fine material and contain a few large (>10 m) and isolated boulders; ii) intermediate-slope terrains (20-45 degrees) are mainly fallen consolidated materials and debris fields, with numerous intermediate-size boulders from <1m to 10m for the majority of them; and iii) high-slope terrains (45-90 degrees) are cliffs that expose a consolidated material and do not show boulders or fine materials. The best range for the tensile strength of overhangs is 3-15 Pa (upper limit of 150 Pa), 4-30 Pa for the shear strength of fine surface materials and boulders, and 30-150 Pa for the compressive strength of overhangs (upper limit of 1500 Pa). The strength-to-gravity ratio is similar for 67P and weak rocks on Earth. As a result of the low compressive strength, the interior of the nucleus may have been compressed sufficiently to initiate diagenesis, which could have contributed to the formation of layers. Our value for the tensile strength is comparable to that of dust aggregates formed by gravitational instability and tends to favor a formation of comets by the accrection of pebbles at low velocities.

  • 38.
    Groussin, O.
    et al.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid 28691, Spain.;Int Space Sci Inst, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    Keller, H. U.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Giuseppe Colombo CISAS, Ctr Ateneo Studi & Attivita Spaziali, I-35131 Padua, Italy..
    Besse, S.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Cremonese, G.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Ip, W. -H
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan..
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Knollenberg, J.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Kueppers, M.
    European Space Astron Ctr ESA, Operat Dept, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Lowry, S.
    Univ Kent, Schoold Phys Sci SEPnet, Ctr Astrophys & Planetary Sci, Canterbury CT2 7NH, Kent, England..
    Marchi, S.
    Southwest Res Inst, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Giuseppe Colombo CISAS, Ctr Ateneo Studi & Attivita Spaziali, I-35131 Padua, Italy.;Osserv Astron Padova, INAF, I-35122 Padua, Italy..
    Mottola, S.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Giuseppe Colombo CISAS, Ctr Ateneo Studi & Attivita Spaziali, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Giuseppe Colombo CISAS, Ctr Ateneo Studi & Attivita Spaziali, I-35131 Padua, Italy..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Toth, I.
    Konkoly Observ Budapest, H-1525 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A36Article in journal (Refereed)
    Abstract [en]

    Aims. We report on the first major temporal morphological changes observed on the surface of the nucleus of comet 67P/Churyumov-Gerasimenko in the smooth terrains of the Imhotep region. Methods. We used images of the OSIRIS cameras onboard Rosetta to follow the temporal changes from 24 May 2015 to 11 July 2015. Results. The morphological changes observed on the surface are visible in the form of roundish features that are growing in size from a given location in a preferential direction at a rate of 5.6-8.1 x 10(-5) m s(-1) during the observational period. The location where the changes started and the contours of the expanding features are bluer than the surroundings, which suggests that ices (H2O and/or CO2) are exposed on the surface. However, sublimation of ices alone is not sufficient to explain the observed expanding features. No significant variations in the dust activity pattern are observed during the period of changes.

  • 39.
    Grun, E.
    et al.
    Max Planck Inst Kernphys, Saupfercheckweg 1, D-69127 Heidelberg, Germany.;Univ Colorado, Lab Atmospher & Space Phys, 1234 Innovat Dr, Boulder, CO 80303 USA..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Altobelli, N.
    ESA, Camino Bajo Castillo S-N, E-28692 Madrid, Spain..
    Altwegg, K.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Bentley, M. S.
    Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria..
    Biver, N.
    Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France..
    Della Corte, V.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy..
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Feldman, P. D.
    Johns Hopkins Univ, Dept Phys & Astron, Baltimore, MD 21218 USA..
    Galand, M.
    Imperial Coll, South Kensington Campus, London SW7 2AZ, England..
    Geiger, B.
    ESA, Camino Bajo Castillo S-N, E-28692 Madrid, Spain..
    Goetz, C.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Grieger, B.
    ESA, Camino Bajo Castillo S-N, E-28692 Madrid, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Henri, P.
    CNRS, LPC2E, Orleans, France..
    Hofstadter, M.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Horanyi, M.
    Univ Colorado, Lab Atmospher & Space Phys, 1234 Innovat Dr, Boulder, CO 80303 USA..
    Jehin, E.
    Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium..
    Krueger, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Lee, S.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Mannel, T.
    Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria..
    Morales, E.
    Jaicoa Observ, Aguadilla, PR USA..
    Mousis, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Mueller, M.
    ESOC, ESA, Robert Bosch Str 5, Darmstadt, Germany..
    Opitom, C.
    Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium..
    Rotundi, A.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy.;Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Schmied, R.
    Austrian Acad Sci, Space Res Inst, Schmiedlstr 6, A-8042 Graz, Austria.;Graz Univ, Inst Phys, Univ Pl 3, A-8010 Graz, Austria..
    Schmidt, F.
    Univ Stuttgart, Inst Raumfahrtsyst IRS, Pfaffenwaldring 29, D-70569 Stuttgart, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Snodgrass, C.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Soja, R. H.
    Univ Stuttgart, Inst Raumfahrtsyst IRS, Pfaffenwaldring 29, D-70569 Stuttgart, Germany..
    Sommer, M.
    Univ Stuttgart, Inst Raumfahrtsyst IRS, Pfaffenwaldring 29, D-70569 Stuttgart, Germany..
    Srama, R.
    Univ Stuttgart, Inst Raumfahrtsyst IRS, Pfaffenwaldring 29, D-70569 Stuttgart, Germany..
    Tzou, C. -Y
    Vincent, J. -B
    Yanamandra-Fisher, P.
    Space Sci Inst, 13456 Cajon Creek Court, Rancho Cucamonga, CA 91739 USA..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Barucci, M. A.
    Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giusepp Colomb, Via Venezia 15, I-35131 Padua, Italy..
    Burch, J.
    Southwest Res Inst, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Colangeli, L.
    European Space Agcy, European Space Res & Technol Ctr, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34143 Trieste, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Feaga, L. M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Ferrari, M.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy..
    Fornasier, S.
    Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France..
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gillon, M.
    Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium..
    Green, S. F.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Hofmann, M.
    Hviid, S. F.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Ivanovski, S.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Knight, M. M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Knollenberg, J.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Koschny, D.
    European Space Agcy, European Space Res & Technol Ctr, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands..
    Kramm, J. -R
    Kuehrt, E.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    ESA, Camino Bajo Castillo S-N, E-28692 Madrid, Spain..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, 38 Rue Federic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Federic Joliot Curie, F-13388 Marseille 13, France..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Manfroid, J.
    Univ Liege, Inst Astrophys & Geophys, B-4000 Liege, Belgium..
    Epifani, E. Mazzotta
    OAR, INAF, Via Frascati 33, I-00078 Rome, Italy..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giusepp Colomb, Via Venezia 15, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Palumbo, P.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy.;Univ Napoli Parthenope, Dip Sci & Tecnol, CDN IC4, I-80143 Naples, Italy..
    Parker, J. Wm.
    Southwest Res Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Poland.
    Rodrigo, R.
    ESA, Camino Bajo Castillo S-N, E-28692 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Rodriguez, J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron S-N, E-18008 Granada, Spain..
    Schindhelm, E.
    Southwest Res Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Shi, X.
    Sordini, R.
    INAF, IAPS, Via Fosso Cavaliere, I-00133 Rome, Italy..
    Steffl, A. J.
    Southwest Res Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Stern, S. A.
    Southwest Res Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Weaver, H. A.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Weissman, P.
    Planetary Sci Inst, 1700 East Ft Lowell,Suite 106, Tucson, AZ 85719 USA..
    Zakharov, V. V.
    Univ Paris Diderot, UPMC, CNRS, LESIA,Observ Paris, 5 Pl Jules Janssen, F-92195 Meudon, France.;UPMC Univ Paris 06, CNRS, Sorbonne Univ, Lab Meteorol Dynam, 4 Pl Jussieu, F-75252 Paris, France..
    The 2016 Feb 19 outburst of comet 67P/CG: an ESA Rosetta multi-instrument study2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S220-S234Article in journal (Refereed)
    Abstract [en]

    On 2016 Feb 19, nine Rosetta instruments serendipitously observed an outburst of gas and dust from the nucleus of comet 67P/Churyumov-Gerasimenko. Among these instruments were cameras and spectrometers ranging from UV over visible to microwave wavelengths, in situ gas, dust and plasma instruments, and one dust collector. At 09: 40 a dust cloud developed at the edge of an image in the shadowed region of the nucleus. Over the next two hours the instruments recorded a signature of the outburst that significantly exceeded the background. The enhancement ranged from 50 per cent of the neutral gas density at Rosetta to factors > 100 of the brightness of the coma near the nucleus. Dust related phenomena (dust counts or brightness due to illuminated dust) showed the strongest enhancements (factors > 10). However, even the electron density at Rosetta increased by a factor 3 and consequently the spacecraft potential changed from similar to-16 V to -20 V during the outburst. A clear sequence of events was observed at the distance of Rosetta ( 34 km from the nucleus): within 15 min the Star Tracker camera detected fast particles (similar to 25 m s(-1)) while 100 mu m radius particles were detected by the GIADA dust instrument similar to 1 h later at a speed of 6 m s(-1). The slowest were individual mm to cm sized grains observed by the OSIRIS cameras. Although the outburst originated just outside the FOV of the instruments, the source region and the magnitude of the outburst could be determined.

  • 40.
    Gunnarsson, M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Bockelee-Morvan, D.
    Biver, N.
    Crovisier, J.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics, The Uppsala Astronomical Observatory.
    Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 12008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 484, no 2, p. 537-546Article in journal (Refereed)
    Abstract [en]

    Context. CO is assumed to be the main driver behind the activity of comet 29P/Schwassmann-Wachmann 1, which resides in a near-circular orbit at 6 AU from the Sun. Several properties of the outgassing of CO can be deduced from its millimetre-wave emission. Earlier studies have indicated CO production from the nucleus as well as an extended source. Aims. We have sought to further investigate the nature of the CO production in comet 29P/Schwassmann-Wachmann 1, through the use of newly available instrumentation. Methods. We used the HERA receiver array on the 30-m IRAM telescope to map the 230 GHz CO(J = 2-1) line in the comet with an unprecedented sensitivity and spatial coverage, and a high spectral resolution (20 kHz, i.e., 25 m s(-1)). A 36-point map, 60 by 60 '', was obtained in June 2003, and a 25-point map, 96 by 96 '', in January 2004. Results. The CO emission line has a characteristic asymmetric profile. Our analysis is based on a coma model, where the outgassing pattern is derived from the shape of this line at the central position of the map. When comparing to the observations, both maps show a line intensity at offset positions that is 2-3 times stronger than the model prediction. Different explanations for this are evaluated, and it is found that for the global coma character, an extremely low gas temperature in the inner coma reproduces the observed radial profile. A cold inner coma depletes the population of the CO J = 2 rotational level in the region closest to the nucleus, making spectra observed at offset positions relatively stronger. From the global appearance of the maps, the coma was found to be largely axisymmetric, and the presence of a strong extended source of CO, as indicated from earlier observations using the SEST telescope, was not seen. When examining the maps in more detail, a possible exception to this was seen in an area similar to 30 '' south of the comet, where an excess in emission is present in both maps. Model fits to the spectra based on the cold inner coma that we find, with an intital kinetic temperature T(kin) = 4 K, give a measure of Q(CO), the CO production rate. Q(CO) was found to be (3.9 +/- 0.2) x 10(28) mol s(-1) in June 2003, and (3.7 +/- 0.2) x 10(28) mol s(-1) in January 2004. These values are a factor similar to 1.5 higher than that derived using only the information available from non-mapped data, and this adjustment applies also to previously published production rates.

  • 41.
    Gustafsson, Bengt
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. NORDITA, Roslagstullsbacken 23, 106 91 Stockholm, Sweden .
    Church, Ross P.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Davies, Melvyn B.
    Lund Observ, Dept Astron & Theoret Phys, Box 43, S-22100 Lund, Sweden..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Gravitational scattering of stars and clusters and the heating of the Galactic disk2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 593, article id A85Article in journal (Refereed)
    Abstract [en]

    Context. Could the velocity spread, increasing with time, in the Galactic disk be explained as a result of gravitational interactions of stars with giant molecular clouds (GMCs) and spiral arms? Do the old open clusters high above the Galactic plane provide clues to this question? Aims. We explore the effects on stellar orbits of scattering by inhomogeneities in the Galactic potential due to GMCs, spiral arms and the Galactic bar, and whether high-altitude clusters could have formed in orbits closer to the Galactic plane and later been scattered. Methods. Simulations of test-particle motions are performed in a realistic Galactic potential. The effects of the internal structure of GMCs are explored. The destruction of clusters in GMC collisions is treated in detail with N-body simulations of the clusters. Results. The observed velocity dispersions of stars as a function of time are well reproduced. The GMC structure is found to be significant, but adequate models produce considerable scattering effects. The fraction of simulated massive old open clusters, scattered into orbits with vertical bar z vertical bar > 400 pc, is typically 0.5%, in agreement with the observed number of high-altitude clusters and consistent with the present formation rate of massive open clusters. Conclusions. The heating of the thin Galactic disk is well explained by gravitational scattering by GMCs and spiral arms, if the local correlation between the GMC mass and the corresponding voids in the gas is not very strong. Our results suggest that the high-altitude metal-rich clusters were formed in orbits close to the Galactic plane and later scattered to higher orbits. It is possible, though not very probable, that the Sun formed in such a cluster before scattering occurred.

  • 42.
    Gutierrez, P. J.
    et al.
    Inst Astrofis Andalucia CSIC, Glorieta Astron S-N, Granada 18080, Spain..
    Jorda, L.
    Aix Marseille Univ, LAM, UMR 7326, CNRS, F-13388 Marseille, France..
    Gaskell, R. W.
    Planetary Sci Inst, Tucson, AZ 85719 USA..
    Davidsson, Björn J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Capanna, C.
    Aix Marseille Univ, LAM, UMR 7326, CNRS, F-13388 Marseille, France..
    Hviid, S. F.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Maquet, L.
    IMCCE Observ Paris, 61 Ave Observ, F-75014 Paris, France..
    Mottola, S.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Preusker, F.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Scholten, F.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Glorieta Astron S-N, Granada 18080, Spain..
    Moreno, F.
    Inst Astrofis Andalucia CSIC, Glorieta Astron S-N, Granada 18080, Spain..
    Rodrigo, R.
    ESA, ESAC, Ctr Astrobiol INTA CSIC, POB 78, Madrid 28691, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, LAM, UMR 7326, CNRS, F-13388 Marseille, France..
    Koschny, D.
    European Space Res & Technol Ctr ESA, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk ZH, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. T.
    Aix Marseille Univ, LAM, UMR 7326, CNRS, F-13388 Marseille, France..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. L.
    CNRS UVSQ IPSL, LATMOS, 11 Blvd dAlembert, F-78280 Guyancourt, France..
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trent, Via Sommarive 9, I-38123 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, LAM, UMR 7326, CNRS, F-13388 Marseille, France..
    Gutierrez-Marques, P.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Ip, W. H.
    Natl Cent Univ, Grad Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Knollenberg, J.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kueht, E.
    German Aerosp Ctr DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    European Space Astron Ctr ESA, Operat Dept, POB 78, Madrid 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lopez-Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Glorieta Astron S-N, Granada 18080, Spain..
    Magrin, S.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Marchi, S.
    Southwest Res Inst, Solar Syst Explorat Res Virtual Inst, 1050 Walnut St,Suite 300, Boulder, CO 80302 USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, Via Venezia 15, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Att Spaziali Giuseppe Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Pommerol, A.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Sabau, D.
    Inst Nacl Tecn Aeroespacial, Carretera Ajalvir,Pk 4, Madrid 28850, Spain..
    Thomas, N.
    Univ Bern, Inst Phys, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland..
    Toth, I.
    MTA CSFK Konkoly Observ, H-1121 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. B.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Possible interpretation of the precession of comet 67P/Churyumov-Gerasimenko2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 590, article id A46Article in journal (Refereed)
    Abstract [en]

    Context. Data derived from the reconstruction of the nucleus shape of comet 67P/Churyumov-Gerasimenko (67P) from images of the OSIRIS camera onboard ROSETTA show evidence that the nucleus rotates in complex mode. First, the orientation of the spin axis is not fixed in an inertial reference frame, which suggests a precessing motion around the angular momentum vector with a periodicity of approximately 257 h +/- 12 h. Second, periodograms of the right ascension and declination (RA/Dec) coordinates of the body-frame Z axis show a very significant (higher than 99.99%) periodicity at 276 h +/- 12 h, different from the rotational period of 12.40 h as previously determined from light-curve analysis. Aims. The main goal is to interpret the data and associated periodicities of the spin axis orientation in space. Methods. We analyzed the spin axis orientation in space and associated periodicities and compared them with solutions of Euler equations under the assumption that the body rotates in torque-free conditions. Statistical tests comparing the observationally derived spin axis orientation with the outcome from simulations were applied to determine the most likely inertia moments, excitation level, and periods. Results. Under the assumption that the body is solid-rigid and rotates in torque-free conditions, the most likely interpretation is that 67P is spinning around the principal axis with the highest inertia moment with a period of about 13 h. At the same time, the comet precesses around the angular momentum vector with a period of about 6.35 h. While the rotating period of such a body would be about 12.4 h, RA/Dec coordinates of the spin axis would have a periodicity of about 270 h as a result of the combination of the two aforementioned motions. Conclusions. The most direct and simple interpretation of the complex rotation of 67P requires a ratio of inertia moments significantly higher than that of a homogeneous body.

  • 43.
    Hu, X.
    et al.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Shi, X.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fulle, M.
    INAF Osservatorio Astron Trieste, Via Tiepolo 11, I-34014 Trieste, Italy..
    Blum, J.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Kührt, E.
    Inst Plasmaforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Davidsson, B.
    Jet Prop Lab, M-S 183-301,4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Güttler, C.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gundlach, B.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Pajola, M.
    Ames Res Ctr, Moffett Field, CA 94035 USA..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Vincent, J. -B
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Massironi, M.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Groussin, O.
    Aix Marseille Univ, LAM, CNRS, UMR 7326, F-13388 Marseille, France..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Höfner, S.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Mottola, S.
    Inst Plasmaforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P. L.
    CNRS, UMR 7326, Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rodrigo, R.
    INTA, CSIC, Ctr Astrobiol, 28850 Torrejon Ardoz, Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    ESA, European Space Res & Technol Ctr, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. PAS Space Reserch Ctr, Bartycka 18A, PL-00716 Warsaw, Poland.
    A'Hearn, M.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barucci, M. A.
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, Observ Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo & Attivita Spaziali Giuseppe Colombo C, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    IFN UOS Padova LUXOR, CNR, Via Trasea 7, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80301 USA..
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gutierrez-Marques, P.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Granada 18008, Spain..
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Inst Plasmaforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, LAM, CNRS, UMR 7326, F-13388 Marseille, France..
    Knollenberg, J.
    Inst Plasmaforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch MPS, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Küppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Granada 18008, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Granada 18008, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    IFN UOS Padova LUXOR, CNR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.;Univ Bern, Ctr Space & Habitabil, CH-3012 Bern, Switzerland..
    Seasonal erosion and restoration of the dust cover on comet 67P/Churyumov-Gerasimenko as observed by OSIRIS onboard Rosetta2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 604, article id A114Article in journal (Refereed)
    Abstract [en]

    Context: Dust deposits or dust cover are a prevalent morphology in the northern hemi-nucleus of comet 67P /Churyumov-Gerasimenko (67P). The evolution of the dust deposits was captured by the OSIRIS camera system onboard the Rosetta spacecraft having escorted the comet for over two years. The observations shed light on the fundamental role of cometary activity in shaping and transforming the surface morphology.

    Aims: We aim to present OSIRIS observations of surface changes over the dust deposits before and after perihelion. The distribution of changes and a timeline of their occurrence are provided. We perform a data analysis to quantify the surface changes and investigate their correlation to water activity from the dust deposits. We further discuss how the results of our investigation are related to other findings from the Rosetta mission.

    Methods: Surface changes were detected via systematic comparison of images, and quantified using shape-from-shading technique. Thermal models were applied to estimate the erosion of water ice in response to the increasing insolation over the areas where surface changes occurred. Modeling results were used for the interpretation of the observed surface changes.

    Results: Surface changes discussed here were concentrated at mid-latitudes, between about 20 degrees N and 40 degrees N, marking a global transition from the dust-covered to rugged terrains. The changes were distributed in open areas exposed to ample solar illumination and likely subject to enhanced surface erosion before perihelion. The occurrence of changes followed the southward migration of the sub-solar point across the latitudes of their distribution. The erosion at locations of most changes was at least about 0 : 5 m, but most likely did not exceed several meters. The erosive features before perihelion had given way to a fresh, smooth cover of dust deposits after perihelion, suggesting that the dust deposits had been globally restored by at least about 1 m with ejecta from the intensely illuminated southern hemi-nucleus around perihelion, when the north was inactive during polar night.

    Conclusions: The erosion and restoration of the northern dust deposits are morphological expressions of seasonality on 67P. Based on observations and thermal modeling results, it is inferred that the dust deposits contained a few percent of water ice in mass on average. Local inhomogeneity in water abundance at spatial scales below tens of meters is likely. We suspect that dust ejected from the deposits may not have escaped the comet in bulk. That is, at least half of the ejected mass was afloat in the inner-coma or /and redeposited over other areas of the nucleus.

  • 44. Ip, W. -H
    et al.
    Lai, I. -L
    Lee, J. -C
    Cheng, Y. -C
    Li, Y.
    Macau Univ Sci & Technol, Space Sci Inst, Macau, Peoples R China..
    Lin, Z. -Y
    Vincent, J. -B
    Besse, S.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.;Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    Ctr Astrobiol INTA CSIC, Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, D-38106 Braunschweig, Germany..
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vic Dell Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Sommar 9, I-38123 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, S. F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, M.
    ESAC, POB 78, Madrid 28691, Spain..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Lopez-Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18008, Spain..
    Lowry, S.
    Univ Kent, Sch Phys Sci, Ctr Astrophys & Planetary Sci, Canterbury CT2 7NH, Kent, England..
    Marchi, S.
    Southwest Res Inst, Boulder, CO USA..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, D-38106 Braunschweig, Germany..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Pajola, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Thomas, N.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Toth, E.
    MTA CSFK Konkoly Observ, H-1121 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Physical properties and dynamical relation of the circular depressions on comet 67P/Churyumov-Gerasimenko2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 591, article id A132Article in journal (Refereed)
    Abstract [en]

    Aims. We aim to characterize the circular depressions of comet 67P/Churyumov-Gerasimenko and investigate whether such surface morphology of a comet nucleus is related to the cumulative sublimation effect since becoming a Jupiter family comet (JFC). Methods. The images from the Rosetta/OSIRIS science camera experiment are used to construct size frequency distributions of the circular depression structures on comet 67P and they are compared with those of the JFCs 81P/Wild 2, 9P/Tempel 1, and 103P/Hartley 2. The orbital evolutionary histories of these comets over the past 100 000 yr are analyzed statistically and compared with each other. Results. The global distribution of the circular depressions over the surface of 67P is charted and classified. Descriptions are given to the characteristics and cumulative size frequency distribution of the identified features. Orbital statistics of the JFCs visited by spacecraft are derived. Conclusions. The size frequency distribution of the circular depressions is found to have a similar power law distribution to those of 9P/Tempel 1 and 81P/Wild 2. This might imply that they could have been generated by the same process. Orbital integration calculation shows that the surface erosion histories of 81P/Wild 2, and 9P/Tempel 1 could be shorter than those of 67P, 103 P/Hartley 2 and 19P/Borrelly. From this point of view, the circular depressions could be dated back to the pre-JFC phase or the transneptunian phase of these comets. The north-south asymmetry in the distribution of the circular depressions could be associated with the heterogeneous structure of the nucleus of comet 67P and/or the solar insolation history.

  • 45.
    Jorda, L.
    et al.
    Univ Aix Marseille, Lab Astrophys Marseille, UMR7326, CNRS, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Gaskell, R.
    Planetary Sci Inst, 1700 East Ft Lowell,Suite 106, Tucson, AZ 85719 USA..
    Capanna, C.
    Univ Aix Marseille, Lab Astrophys Marseille, UMR7326, CNRS, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Hviid, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lamy, P.
    Univ Aix Marseille, Lab Astrophys Marseille, UMR7326, CNRS, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Durech, J.
    Charles Univ Prague, Fac Math & Phys, Astron Inst, V Holesovickch 2, CR-18000 Prague, Czech Republic..
    Faury, G.
    AKKA Technol, 6 Rue Roger Camboulives, F-31100 Toulouse, France..
    Groussin, O.
    Univ Aix Marseille, Lab Astrophys Marseille, UMR7326, CNRS, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Gutierrez, P.
    CSIC, Inst Astrofis Andalucia, Aptd 3004, E-18080 Granada, Spain..
    Jackman, C.
    KinetX Aerosp Inc, 21 W Easy St, Simi Valley, CA 93065 USA..
    Keihm, S. J.
    CALTECH, Jet Prop Lab, 4800 Oak Grove Dr, Pasadena, CA 91109 USA..
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Marchi, S.
    Southwest Res Inst, 1050 Walnut St, Boulder, CO 80302 USA..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Palmer, E.
    Planetary Sci Inst, 1700 East Ft Lowell,Suite 106, Tucson, AZ 85719 USA..
    Schloerb, F. P.
    Univ Massachusetts, 619 Lederle Grad Res Tower, Amherst, MA 01003 USA..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, J. -B
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Rodrigo, R.
    CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    ESA RSSD, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. L.
    CNRS UVSQ IPSL, LATMOS, 11 Blvd Alembert, F-78280 Guyancourt, France..
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, G.
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B.
    PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Debei, S.
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, Via Mesiano 77, I-38100 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, Italy..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Ip, W. -H
    Natl Cent Univ, Inst Space Sci, Chungli 32054, Taiwan.
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kueppers, M.
    ESA ESAC, POB 78, Villanueva De La Caliada 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Aptd 3004, E-18080 Granada, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, Aptd 3004, E-18080 Granada, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Wenzel, K-P
    ESA SSO, Keplerlaan 1,Postbus 299, NL-2201 AZ Noordwijk, Netherlands.
    The global shape, density and rotation of Comet 67P/Churyumov-Gerasimenko from preperihelion Rosetta/OSIRIS observations2016In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 277, p. 257-278Article in journal (Refereed)
    Abstract [en]

    The Rosetta spacecraft reached Comet 67P/Churyumov-Gerasimenko (hereafter 67P/C-G) in August 2014 at an heliocentric distance of 3.6 a.u. and was then put in orbit around its nucleus to perform detailed observations. Among the collected data are the images acquired by the OSIRIS instrument up to the perihelion passage of the comet in August 2015, which allowed us to map the entire nucleus surface at high-resolution in the visible. Stereophotoclinometry methods have been used to reconstruct a global high-resolution shape model and to monitor its rotational parameters using data collected up to perihelion. The nucleus has a conspicuous bilobate shape with overall dimensions along its principal axes of (4.34 +/- 0.02) x (2.60 +/- 0.02) x (2.12 +/- 0.06) km. The best-fit ellipsoid dimensions of the individual lobes along their principal axes of inertia are found to be 4.10 x 3.52 x 1.63 km and 2.50 x 2.14 x 1.641cm. Their volume amounts to 66% and 27% of the total volume of the nucleus. The two lobes are connected by a "neck" whose volume has been estimated to represent similar to 7% of the total volume of the comet. Combining the derived volume of 18.8 +/- 0.3 km(3) with the mass of 9.982 +/- 0.003 x 10(12) kg determined by the Rosetta/RSI experiment, we obtained a bulk density of the nucleus of 532 +/- 7 kg m(-3). Together with the companion value of 535 35 kg m-3 deduced from the stereophotogrammetry shape model of the nucleus (Preusker et al. [2015] Astron. Astrophys. 583, A33), these constitute the first reliable and most accurate determination of the density of a cometary nucleus to date. The calculated porosity is quite large, ranging approximately from 70% to 75% depending upon the assumed density of the dust grains and the dust-to-ice mass ratio. The nature of the porosity, either micro or macro or both, remains unconstrained. The coordinates of the center of gravity are not compatible with a uniform nucleus density. The direction of the offset between the center of gravity and the center of figure suggests that the big lobe has a slightly higher bulk density compared to the small one. the center of mass position cannot be explained by different, but homogenous densities in the two lobes. The initial rotational period of 12.4041 +/- 0.0001 h of the nucleus persisted until October 2014. It then slightly increased to a maximum of 12.4304h reached on 19 May 2015 and finally dropped to 12.305 h just before perihelion on August 10, 2015. A periodogram analysis of the (RA, Dec) direction of the Z-axis of the comet obtained in parallel with the shape reconstruction exhibits a highly significant minima at 11.5 +/- 0.5 day clearly indicating an excited rotational state with an amplitude of 0.15 +/- 0.03 degrees.

  • 46.
    Keller, H.
    et al.
    Max-Planck-Institut für Sonnensystemforschung.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Davidsson, Björn J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Wenzel, Klaus-Peter
    Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta2007In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 187, no 1, p. 87-103Article in journal (Refereed)
    Abstract [en]

    The OSIRIS cameras on the Rosetta spacecraft observed Comet 9P/Tempel 1 from 5 days before to 10 days after it was hit by the Deep Impactprojectile. The Narrow Angle Camera (NAC) monitored the cometary dust in 5 different filters. The Wide Angle Camera (WAC) observed through filters sensitive to emissions from OH, CN, Na, and OI together with the associated continuum. Before and after the impact the comet showedregular variations in intensity. The period of the brightness changes is consistent with the rotation period of Tempel 1. The overall brightness ofTempel 1 decreased by about 10% during the OSIRIS observations. The analysis of the impact ejecta shows that no new permanent coma structureswere created by the impact. Most of the material moved with ∼200 m s−1 . Much of it left the comet in the form of icy grains which sublimatedand fragmented within the first hour after the impact. The light curve of the comet after the impact and the amount of material leaving the comet(4.5–9 × 106 kg of water ice and a presumably larger amount of dust) suggest that the impact ejecta were quickly accelerated by collisions withgas molecules. Therefore, the motion of the bulk of the ejecta cannot be described by ballistic trajectories, and the validity of determinations ofthe density and tensile strength of the nucleus of Tempel 1 with models using ballistic ejection of particles is uncertain.

  • 47.
    Keller, H. U.
    et al.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany.;Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Mottola, S.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Schroeder, S. E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Skorov, Y.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kuehrt, E.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS Colombo, I-35131 Padua, Italy..
    Hviid, S. F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Preusker, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Scholten, F.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Rodrigo, R.
    Int Space Sci Inst, CH-3012 Bern, Switzerland.;CSIC INTA, Ctr Astrobiol, Madrid 28850, Spain..
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy. PAS Space Res Ctr, PL-00716 Warsaw, Poland..
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Studies & Act Space CISAS Colombo, I-35131 Padua, Italy..
    Cremonese, G.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Debei, S.
    Univ Padua, Dept Mech Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, I-38100 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, Observ Paris, LESIA,CNRS, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Granada 18080, Spain..
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Knollenberg, J.
    DLR, Inst Planetary Res, D-12489 Berlin, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kueppers, M.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    Lara, L. M.
    Inst Astrofis Andalucia CSIC, Granada 18080, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Lopez Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Granada 18080, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy..
    Michalik, H.
    Univ Padua, Dept Phys & Astron, I-35122 Padua, Italy.;Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Naletto, G.
    Univ Padua, Dept Informat Engn, I-35131 Padua, Italy..
    Sabau, L.
    Inst Nacl Tecn Aeroespacial, Torrejon De Ardoz 28850, Spain..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Vincent, J. -B
    Wenzel, K. -P
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Insolation, erosion, and morphology of comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A34Article in journal (Refereed)
    Abstract [en]

    Context. The complex shape of comet 67P and its oblique rotation axis cause pronounced seasonal effects. Irradiation and hence activity vary strongly. Aims. We investigate the insolation of the cometary surface in order to predict the sublimation of water ice. The strongly varying erosion levels are correlated with the topography and morphology of the present cometary surface and its evolution. Methods. The insolation as a function of heliocentric distance and diurnal (spin dependent) variation is calculated using >10(5) facets of a detailed digital terrain model. Shading, but also illumination and thermal radiation by facets in the field of view of a specific facet are iteratively taken into account. We use a two-layer model of a thin porous dust cover above an icy surface to calculate the water sublimation, presuming steady state and a uniform surface. Our second model, which includes the history of warming and cooling due to thermal inertia, is restricted to a much simpler shape model but allows us to test various distributions of active areas. Results. Sublimation from a dirty ice surface yields maximum erosion. A thin dust cover of 50 pm yields similar rates at perihelion. Only about 6% of the surface needs to be active to match the observed water production rates at perihelion. A dust layer of 1 mm thickness suppresses the activity by a factor of 4 to 5. Erosion on the south side can reach more than 10 m per orbit at active spots. The energy input to the concave neck area (Hapi) during northern summer is enhanced by about 50% owing to self-illumination. Here surface temperatures reach maximum values along the foot of the Hathor wall. Integrated over the whole orbit this area receives the least energy input. Based on the detailed shape model, the simulations identify "hot spots" in depressions and larger pits in good correlation with observed dust activity. Three-quarters of the total sublimation is produced while the sub-solar latitude is south, resulting in a distinct dichotomy in activity and morphology. Conclusions. The northern areas display a much rougher morphology than what is seen on Imhotep, an area at the equator that will be fully illuminated when 67P is closer to the Sun. Self-illumination in concave regions enhance the energy input and hence erosion. This explains the early activity observed at Hapi. Cliffs are more prone to erosion than horizontal, often dust covered, areas, which leads to surface planation. Local activity can only persist if the forming cliff walls are eroding. Comet 67P has two lobes and also two distinct sides. Transport of material from the south to the north is probable. The morphology of the Imhotep plain should be typical for the terrains of the yet unseen southern hemisphere.

  • 48.
    Keller, H. U.
    et al.
    Max-Planck-Institut für Sonnensystemforschung.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Zaccariotto, M.
    CISAS, University of Padova.
    OSIRIS: The scientific camera system onboard Rosetta2007In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 128, no 1-4, p. 433-506Article in journal (Refereed)
    Abstract [en]

    The Optical, Spectroscopic, and Infrared Remote Imaging System OSIRIS is the scientific camera system onboard the Rosetta spacecraft (Figure 1). The advanced high performance imaging system will be pivotal for the success of the Rosetta mission. OSIRIS will detect 67P/Churyumov-Gerasimenko from a distance of more than 106 km, characterise the comet shape and volume, its rotational state and find a suitable landing spot for Philae, the Rosetta lander. OSIRIS will observe the nucleus, its activity and surroundings down to a scale of ~2 cm px−1. The observations will begin well before the onset of cometary activity and will extend over months until the comet reaches perihelion. During the rendezvous episode of the Rosetta mission, OSIRIS will provide key information about the nature of cometary nuclei and reveal the physics of cometary activity that leads to the gas and dust coma. OSIRIS comprises a high resolution Narrow Angle Camera (NAC) unit and a Wide Angle Camera (WAC) unit accompanied by three electronics boxes. The NAC is designed to obtain high resolution images of the surface of comet 67P/Churyumov-Gerasimenko through 12 discrete filters over the wavelength range 250–1000 nm at an angular resolution of 18.6 μrad px−1. The WAC is optimised to provide images of the near-nucleus environment in 14 discrete filters at an angular resolution of 101 μrad px−1. The two units use identical shutter, filter wheel, front door, and detector systems. They are operated by a common Data Processing Unit. The OSIRIS instrument has a total mass of 35 kg and is provided by institutes from six European countries.

  • 49.
    Knollenberg, J.
    et al.
    DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany..
    Lin, Z. Y.
    Hviid, S. F.
    Oklay, N.
    Vincent, J. -B
    Bodewits, D.
    Mottola, S.
    Pajola, M.
    Sierks, H.
    Barbieri, C.
    Lamy, P.
    Rodrigo, R.
    Koschny, D.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland.
    A'Hearn, M. F.
    Barucci, M. A.
    Bertaux, J. L.
    Bertini, I.
    Cremonese, G.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Da Deppo, V.
    Debei, S.
    De Cecco, M.
    Fornasier, S.
    Fulle, M.
    Groussin, O.
    Gutierrez, P. J.
    Ip, W. -H
    Jorda, L.
    Keller, H. U.
    Kuehrt, E.
    Kramm, J. R.
    Kuppers, M.
    Lara, L. M.
    Lazzarin, M.
    Moreno, J. J. Lopez
    Marzari, F.
    Naletto, G.
    Thomas, N.
    Guettler, C.
    Preusker, F.
    Scholten, F.
    Tubiana, C.
    A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 596, article id A89Article in journal (Refereed)
    Abstract [en]

    Context. On 12 March 2015 the OSIRIS WAC camera onboard the ESA Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko observed a small outburst originating from the Imhotep region at the foot of the big lobe of the comet. These measurements are unique since it was the first time that the initial phase of a transient outburst event could be directly observed. Aims. We investigate the evolution of the dust jet in order to derive clues about the outburst source mechanism and the ejected dust particles, in particular the dust mass, dust-to-gas ratio and the particle size distribution. Methods. Analysis of the images and of the observation geometry using comet shape models in combination with gasdynamic modeling of the transient dust jet were the main tools used in this study. Synthetic images were computed for comparison with the observations. Results. Analysis of the geometry revealed that the source region was not illuminated until 1.5 h after the event implying true nightside activity was observed. The outburst lasted for less than one hour and the average dust production rate during the initial four minutes was of the order of 1 kg/s. During this time the outburst dust production rate was approximately constant, no sign for an initial explosion could be detected. For dust grains between 0.01-1 mm a power law size distribution characterized by an index of about 2.6 provides the best fit to the observed radiance profiles. The dust-to-gas ratio of the outburst jet is in the range 0.6-1.8.

  • 50. Krolikowska, Malgorzata
    et al.
    Sitarski, Grzegorz
    Pittich, Eduard M.
    Szutowicz, Slawomira
    Ziolkowski, Krzysztof
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Gabryszewski, Ryszard
    Rickman, Bozenna
    New catalogue of one-apparition comets discovered in the years 1901-1950 I. Comets from the Oort spike2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 571, p. A63-Article in journal (Refereed)
    Abstract [en]

    Context: The orbits of one-apparition comets discovered in the early part of the last century have formerly been determined with very different numerical methods and assumptions on the model of the solar system, including the number of planets taken into account. Moreover, observations of the comet-minus-star-type sometimes led to determination of the comet position that are less precise than what we can derive today by using a more modern star catalogue. Aims. We aim to provide a new catalogue of cometary orbits that are derived using a completely homogeneous data treatment, accurate numerical integration, and a modern model of the solar system. Methods. We collected the complete sets of observations for investigated comets from the original publications. Then we recalculated the cometary positions for the comet-minus-star-type of observations using the Positions and Proper Motions Star Catalogue, and applied a uniform method for the data selection and weighting. As a final result, new osculating orbits were determined. Secondly, dynamical calculations were performed to the distance of 250 AU from the Sun to derive original and future barycentric orbits for evolution backward and forward in time. These numerical calculations for a given object start from a swarm of virtual comets constructed using our osculating (nominal) orbit. In this way, we obtained the orbital element uncertainties of original and future barycentric orbits. Results. We present homogeneous sets of orbital elements for osculating, original, and future orbits for 38 one-apparition comets. Non-gravitational orbits are derived for thirteen of them.

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