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  • 1. 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.

  • 2.
    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.

  • 3. Bertini, Ivano
    et al.
    Sabolo, Walter
    Gutierrez, Pedro J.
    Marzari, Francesco
    Snodgrass, Colin
    Tubiana, Cecilia
    Moissl, Richard
    Pajola, Maurizio
    Lowry, Stephen C.
    Barbieri, Cesare
    Ferri, Francesca
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Sierks, Holger
    Search for satellites near (21) Lutetia using OSIRIS/Rosetta images2012In: Planetary and Space Science, ISSN 0032-0633, E-ISSN 1873-5088, Vol. 66, no 1, p. 64-70Article in journal (Refereed)
    Abstract [en]

    On 2010 July 10 the ESA Rosetta mission flew by the large asteroid (21) Lutetia. One of the scientific goals of the onboard OSIRIS instrument was the search for satellites of the asteroid, with more than 20 images specifically dedicated to this topic. An observational campaign was devised with a selection of filters and exposure times tailored to maximize the possibility of detecting small companions and determining their bound orbits. Data were analyzed with suitable methods to remove cosmic ray hits and known background objects, in order to search for persistent detections of potential interesting flux sources. We found no unambiguous detections of a satellite larger than similar to 160 m inside the entire sphere of gravitational influence. Our search confirmed the absence of bound companions larger than similar to 30 m inside 20 primary radii. These limits are a factor of similar to 30 smaller than the values reported so far from large ground-based telescopes using adaptive optics and from the Hubble Space Telescope.

  • 4. Blum, J.
    et al.
    Schräpler, R.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Trigo-Rodrigues, J.M
    The physics of protoplanetesimal dust agglomerates: I. Mechanical properties and relations to primitive bodies in the solar system2006In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 652, no 2, p. 1768-1781Article in journal (Refereed)
    Abstract [en]

    We present laboratory experiments on the formation of macroscopic dust aggregates. The centimeter-sized highly porous bodies are produced by random ballistic deposition from individual micrometer-sized dust particles. We find packing densities between 0.07 and 0.15 for uncompressed samples, dependent on the shape and size distribution of the constituent dust grains. Impacts into these bodies are simulated by uniaxial compression experiments. We find that the maximum compression, equivalent to the highest protoplanetary impact velocities of similar to 50ms(-1), increases the packing density to 0.20-0.33. Tensile strength measurements with our laboratory samples yield values in the range 200-1100 Pa for slightly compressed samples. We review packing densities and tensile strengths found for primitive solar system bodies, e. g., for comets, primitive meteorites, and meteoroids. We find a consistency between packing densities and tensile strengths of our laboratory samples with those from cometary origin.

  • 5.
    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.

  • 6.
    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.

  • 7.
    Davidsson, Björn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    The bulk density of cometary nuclei2006In: Advances in Geosciences: Vol. 3: Planetary Science, World Scientific Publishing, Singapore , 2006Chapter in book (Refereed)
  • 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
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Gutierrez, P.J.
    Estimating the nucleus density of Comet 19P/Borrelly2004In: Icarus, Vol. 168, p. 392-408Article in journal (Refereed)
  • 10.
    Davidsson, Björn
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Gutierrez, P.J.
    Nucleus properties of Comet 67P/Churyumov-Gerasimenko estimated from non-gravitational force modeling2005In: Icarus, Vol. 176, p. 453-477Article in journal (Refereed)
  • 11.
    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. 

  • 12.
    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.

  • 13.
    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.

  • 14.
    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.

  • 15.
    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.

  • 16.
    Davidsson, Björn
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Skorov, Yuri
    A practical tool for simulating the presence of gas comae in thermophysical modeling of cometary nuclei2004In: Icarus, ISSN 0019-1035, Vol. 168, no 1, p. 163-185Article in journal (Refereed)
    Abstract [en]

    A longstanding problem in thermophysical modeling of cometary nuclei has been to accurately formulate the boundary conditions at the nucleus/coma interface. A correct treatment of the problem, where the Knudsen layer gas just above the cometary surface (which is not in thermodynamic equilibrium) is modeled in parallel with the nucleus, is extremely time-consuming and has so far been avoided. Instead, simplifying assumptions regarding the coma properties are used, e.g., the surface gas density is assumed equal to zero or set to the local saturation value, and the coma backflux is neglected or given some realistic but approximate value. The resulting inaccuracy regarding the exchange of mass, energy, and momentum between the nucleus and the coma, may introduce significant errors in the calculated nucleus temperature profiles, gas production rates, and momentum transfer efficiencies. In this paper, we present a practical, accurate, and time-efficient tool which makes it possible to consider the nucleus and the innermost coma of a comet (the former assumed to consist of a porous mixture of crystalline water ice and dust) as a coupled, physically consistent system. The tool consists of interpolation tables for the surface gas density and pressure, the recondensing coma backflux, and the cooling energy flux due to diffusely scattered coma molecules. The tables cover a wide range of surface temperatures and sub-surface temperature profiles, and can be used to improve the boundary conditions used in thermophysical models. The interpolation tables have been obtained by calculating the transmission distribution functions of gas emerging from sublimating porous ice/dust mixtures with various temperature profiles, which then are used as source functions in a Direct Simulation Monte Carlo model of inelastic intermolecular collisions in the Knudsen layer.

  • 17.
    Davidsson, Björn
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Skorov, Yuri
    On the light-absorbing surface layer of cometary nuclei: I. Radiative transfer2002In: Icarus, ISSN 0019-1035, Vol. 156, no 1, p. 223-248Article in journal (Refereed)
    Abstract [en]

    A small but increasing volume of observations of cometary nuclei has

    accumulated during the last two decades. This development is accelerating

    with upcoming space missions such as Stardust, Contour, and Rosetta. In

    response to the growing need for a theoretical understanding of optical

    properties of cometary nuclei, we have calculated synthetic reflectance

    spectra in the 0.2-2.0 micrometer wavelength region, photometric

    colors in the Johnson-Kron-Cousins UBVRI system, and visual geometric

    albedos, for a large number of porous ice-dust mixtures with different

    composition, regolith grain sizes and grain morphologies, such as

    core-mantle grains, dense clusters of such grains, and large irregular

    particles with internal scatterers. The calculations are based on Mie theory,

    the Discrete Dipole Approximation, Hapke theory, and a numerical solution

    of the equation of radiative transfer in particulate media. In addition,

    wavelength-integrated directional-hemispherical albedos and flux attenuation profiles in the

    regolith as functions of depth, have been calculated in order to improve the

    energy budget and treatment of energy boundary conditions in thermal models

    of cometary nuclei.

    Our results are compared with spectra and colors of observed cometary nuclei.

    Our main conclusions are that only regolith consisting of relatively large

    core-mantle grains, or clusters of smaller core-mantle grains, are capable

    of reproducing the red colors seen in comets; that ice-dust mixtures

    actually can be darker than ice-free regolith under certain circumstances;

    and that solar radiation sometimes penetrates to a depth that is comparable

    to the region in which diurnal temperature variations occur.

  • 18.
    Davidsson, Björn
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Astronomy and Space Physics.
    Skorov, Yuri
    On the light-absorbing surface layer of cometary nuclei: II. Thermal modeling2002In: Icarus, ISSN 0019-1035, Vol. 159, no 1, p. 239-258Article in journal (Refereed)
    Abstract [en]

    The classical way to treat absorption of solar light in thermophysical modelling of cometary nuclei (and other ice-rich bodies such as jovian satellites), has been to assume complete opaqueness of the surface material. However, as shown by Davidsson and Skorov (2002), substantial light penetration can occur in porous ice even if it is very dusty, implying that gradual absorption of energy in a surface layer should be accounted for.

    We present a thorough comparison between a surface energy absorption model and a layer energy absorption model, for various combinations of heliocentric distances, conductivities, opacities, pore sizes and rotational periods relevant for cometary nuclei, by fully solving the coupled differential equations of heat transfer and gas diffusion. We find substantial differences between the models in terms of gas production rate, thermal lag angle, surface temperature, and the origin of coma molecules. For example, the surface energy absorption model overestimates the total gas production by a factor 2-7, underestimates the lag angle by a factor 2-3, and places the origin of coma molecules at the surface, instead of the near--surface interior.

  • 19.
    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.

  • 20. El-Maarry, M. R.
    et al.
    Thomas, N.
    Gracia-Berna, A.
    Marschall, R.
    Auger, A. -T
    Groussin, O.
    Mottola, S.
    Pajola, M.
    Massironi, M.
    Marchi, S.
    Hoefner, S.
    Preusker, F.
    Scholten, F.
    Jorda, L.
    Kuehrt, E.
    Keller, H. U.
    Sierks, H.
    A'Hearn, M. F.
    Barbieri, C.
    Barucci, M. A.
    Bertaux, J. -L
    Bertini, I.
    Cremonese, G.
    Da Deppo, V.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Debei, S.
    De Cecco, M.
    Deller, J.
    Guettler, C.
    Fornasier, S.
    Fulle, M.
    Gutierrez, P. J.
    Hofmann, M.
    Hviid, S. F.
    Ip, W. -H
    Knollenberg, J.
    Koschny, D.
    Kovacs, G.
    Kramm, J. -R
    Kueppers, M.
    Lamy, P. L.
    Lara, L. M.
    Lazzarin, M.
    Lopez Moreno, J. J.
    Marzari, F.
    Michalik, H.
    Naletto, G.
    Oklay, N.
    Pommerol, A.
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Rodrigo, R.
    Tubiana, C.
    Vincent, J. -B
    Fractures on comet 67P/Churyumov-Gerasimenko observed by Rosetta/OSIRIS2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 13, p. 5170-5178Article in journal (Refereed)
    Abstract [en]

    The Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) experiment onboard the Rosetta spacecraft currently orbiting comet 67P/Churyumov-Gerasimenko has yielded unprecedented views of a comet's nucleus. We present here the first ever observations of meter-scale fractures on the surface of a comet. Some of these fractures form polygonal networks. We present an initial assessment of their morphology, topology, and regional distribution. Fractures are ubiquitous on the surface of the comet's nucleus. Furthermore, they occur in various settings and show different topologies suggesting numerous formation mechanisms, which include thermal insulation weathering, orbital-induced stresses, and possibly seasonal thermal contraction. However, we conclude that thermal insolation weathering is responsible for creating most of the observed fractures based on their morphology and setting in addition to thermal models that indicate diurnal temperature ranges exceeding 200K and thermal gradients of similar to 15K/min at perihelion are possible. Finally, we suggest that fractures could be a facilitator in surface evolution and long-term erosion.

  • 21.
    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.

  • 22.
    Frattin, E.
    et al.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy;Univ Padua, Dipartimento Fis & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Cremonese, G.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Simioni, E.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy;CNR, IFN, UOS Padova, LUXOR, Via Trasea 7, I-35131 Padua, Italy.
    Bertini, I.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Lazzarin, M.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Ott, T.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 11, D-26111 Oldenburg, Germany.
    Drolshagen, E.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 11, D-26111 Oldenburg, Germany.
    La Forgia, F.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vicolo Osservatorio 3, I-35122 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 G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Lamy, P.
    CNRS, UMR 7326, Lab Astrophys Marseille, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France.
    Rodrigo, R.
    INTA, CSIC, Ctr Astrobiol, E-28850 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 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.
    TU Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, 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.
    Barucci, M. A.
    UPMC Univ Paris 06, Univ Paris Diderot, Sorbonne Paris Cite, LESIA,Observ Paris,PSL Res Univ,Sorbonne Univ, 5 Pl J Janssen, F-92195 Meudon, France.
    Bertaux, J. -L
    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.
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Ferrari, S.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy.
    Ferri, F.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy.
    Fornasier, S.
    UPMC Univ Paris 06, Univ Paris Diderot, Sorbonne Paris Cite, LESIA,Observ Paris,PSL Res Univ,Sorbonne Univ, 5 Pl J Janssen, F-92195 Meudon, France.
    Fulle, M.
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy.
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, 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.
    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.
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kramm, J. -R
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kuppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, E-28691 Madrid, Spain.
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Lucchetti, A.
    Astron Observ Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy.
    Marzari, F.
    Univ Padua, Dipartimento Fis & Astron G Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Massironi, M.
    Univ Padua, Dept Geosci, Via G Gradenigo 6, I-35131 Padua, Italy.
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany.
    Naletto, G.
    CNR, IFN, UOS Padova, LUXOR, Via Trasea 7, I-35131 Padua, Italy;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, 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 G Colombo, Via Venezia 15, I-35131 Padua, Italy;NASA, Ames Res Ctr, Moffett Field, CA 94035 USA.
    Penasa, L.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy.
    Shi, X.
    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.
    Vincent, J. -B
    Post-perihelion photometry of dust grains in the coma of 67P Churyumov-Gerasimenko2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, p. S195-S203Article in journal (Refereed)
    Abstract [en]

    We present a photometric analysis of individual dust grains in the coma of comet 67P/Churyumov-Gerasimenko using OSIRIS images taken from 2015 July to 2016 January. We analysed a sample of 555 taken during 18 d at heliocentric distances ranging between 1.25 and 2.04 au and at nucleocentric distances between 80 and 437 km. An automated method to detect the tracks was specifically developed. The images were taken by OSIRIS NAC in four different filters: Near-IR (882 nm), Orange (649 nm), FarOrange (649 nm) and Blue (480 nm). It was not always possible to recognize all the grains in the four filters, hence we measured the spectral slope in two wavelengths ranges: in the interval [480-649] nm, for 1179 grains, and in the interval [649-882] nm, for 746 grains. We studied the evolution of the two populations' average spectral slopes. The data result scattered around the average value in the range [480-649] nm, while in the [649-882] nm we observe a slight decreasing moving away from the Sun as well as a slight increasing with the nucleocentric distance. A spectrophotometric analysis was performed on a subsample of 339 grains. Three major groups were defined, based on the spectral slope between [535-882] nm: (i) the steep spectra that may be related with organic material, (ii) the spectra with an intermediate slope, likely a mixture of silicates and organics and (iii) flat spectra that may be associated with a high abundance of water ice.

  • 23.
    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.

  • 24.
    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.

  • 25.
    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.

  • 26.
    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.

  • 27.
    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.

  • 28.
    Groussin, O.
    et al.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Licandro, J.
    Inst Astrofis Canarias, C Via Lactea S-N, Tenerife 38200, Spain..
    Helbert, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Berlin, Germany..
    Reynaud, J. L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Levacher, P.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Reyes Garcia-Talavera, M.
    Inst Astrofis Canarias, C Via Lactea S-N, Tenerife 38200, Spain..
    Ali-Lagoa, V.
    Inst Astrofis Canarias, C Via Lactea S-N, Tenerife 38200, Spain..
    Blanc, P. E.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Brageot, E.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Delbo, M.
    Univ Nice Antipolis, CNRS, Observ Cote Azur, Nice, France..
    Deleuze, M.
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31055 Toulouse, France..
    Delsanti, A.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Diaz Garcia, J. J.
    Inst Astrofis Canarias, C Via Lactea S-N, Tenerife 38200, Spain..
    Dohlen, K.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Ferrand, D.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Green, S. F.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Joven Alvarez, E.
    Inst Astrofis Canarias, C Via Lactea S-N, Tenerife 38200, Spain..
    Knollenberg, J.
    Deutsch Zentrum Luft & Raumfahrt DLR, Berlin, Germany..
    Kuehrt, E.
    Deutsch Zentrum Luft & Raumfahrt DLR, Berlin, Germany..
    Lamy, P.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Lellouch, E.
    Univ Paris Diderot, UPMC, CNRS, Observ Paris,LESIA, Meudon, France..
    Le Merrer, J.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Marty, B.
    Ctr Rech Petrog & Geochim, BP 20, F-54501 Vandoeuvre Les Nancy, France..
    Mas, G.
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31055 Toulouse, France..
    Rossin, C.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Rozitis, B.
    Open Univ, Dept Phys Sci, Planetary & Space Sci, Milton Keynes MK7 6AA, Bucks, England..
    Sunshine, J.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Vernazza, P.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    Vives, S.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille 13, France..
    THERMAP: a mid-infrared spectro-imager for space missions to small bodies in the inner solar system2016In: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 41, no 1, p. 95-115Article in journal (Refereed)
    Abstract [en]

    We present THERMAP, a mid-infrared spectro-imager for space missions to small bodies in the inner solar system, developed in the framework of the MarcoPolo-R asteroid sample return mission. THERMAP is very well suited to characterize the surface thermal environment of a NEO and to map its surface composition. The instrument has two channels, one for imaging and one for spectroscopy: it is both a thermal camera with full 2D imaging capabilities and a slit spectrometer. THERMAP takes advantage of the recent technological developments of uncooled microbolometer arrays, sensitive in the mid-infrared spectral range. THERMAP can acquire thermal images (8-18 mu m) of the surface and perform absolute temperature measurements with a precision better than 3.5 K above 200 K. THERMAP can acquire mid-infrared spectra (8-16 mu m) of the surface with a spectral resolution Delta lambda of 0.3 mu m. For surface temperatures above 350 K, spectra have a signal-to-noise ratio > 60 in the spectral range 9-13 mu m where most emission features occur.

  • 29.
    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.

  • 30.
    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.

  • 31. Gulkis, Samuel
    et al.
    Allen, Mark
    von Allmen, Paul
    Beaudin, Gerard
    Biver, Nicolas
    Bockelee-Morvan, Dominique
    Choukroun, Mathieu
    Crovisier, Jacques
    Davidsson, Björn J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Encrenaz, Pierre
    Encrenaz, Therese
    Frerking, Margaret
    Hartogh, Paul
    Hofstadter, Mark
    Ip, Wing-Huen
    Janssen, Michael
    Jarchow, Christopher
    Keihm, Stephen
    Lee, Seungwon
    Lellouch, Emmanuel
    Leyrat, Cedric
    Rezac, Ladislav
    Schloerb, F. Peter
    Spilker, Thomas
    Subsurface properties and early activity of comet 67P/Churyumov-Gerasimenko2015In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 347, no 6220, article id UNSP aaa0709Article in journal (Refereed)
    Abstract [en]

    Heat transport and ice sublimation in comets are interrelated processes reflecting properties acquired at the time of formation and during subsequent evolution. The Microwave Instrument on the Rosetta Orbiter (MIRO) acquired maps of the subsurface temperature of comet 67P/Churyumov-Gerasimenko, at 1.6 mm and 0.5 mm wavelengths, and spectra of water vapor. The total H2O production rate varied from 0.3 kg s(-1) in early June 2014 to 1.2 kg s(-1) in late August and showed periodic variations related to nucleus rotation and shape. Water outgassing was localized to the "neck" region of the comet. Subsurface temperatures showed seasonal and diurnal variations, which indicated that the submillimeter radiation originated at depths comparable to the diurnal thermal skin depth. A low thermal inertia (similar to 10 to 50 J K-1 m(-2) s(-0.5)), consistent with a thermally insulating powdered surface, is inferred.

  • 32. Gutierrez, P
    et al.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Non-gravitational force modeling of Comet 81P/Wild 2: II. Rotational evolution2007In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 191, no 2, p. 651-664Article in journal (Refereed)
    Abstract [en]

    In this paper, we have studied both the dynamical and the rotational evolution of an 81P/Wild 2-like comet under the effects of the outgassing-induced force and torque. The main aim is to study if it is possible to reproduce the non-gravitational orbital changes observed in this comet, and to establish the likely evolution of both orbital and rotational parameters. To perform this study, a simple thermophysical model has been used to estimate the torque acting on the nucleus. Once the torque is calculated, Euler equations are solved numerically considering a nucleus mass directly estimated from the changes in the orbital elements (as determined from astrometry). According to these simulations, when the water production rate and changes in orbital parameters for 1997, as well as observational rotational parameters for 2004 are imposed as constraints, the change in the orbital period of 81P/Wild 2, ΔP=P˙, will decrease so that P¨=‑5 to ‑1minorbit, which is similar to the actual tendency observed from 1988 up to 1997. This nearly constant decreasing can be explained as due to a slight drift of the spin axis orientation towards larger ecliptic longitudes. After studying the possible spin axis orientations proposed for 1997, simulations suggest that the spin obliquity and argument (I,Φ)=(56°,167°) is the most likely. As for rotational evolution, changes per orbit smaller than 10% of the actual spin velocity are probable, while the most likely value corresponds to a change between 2 and 7% of the spin velocity. Equally, net changes in the spin axis orientation of 4° 8° per orbit are highly expected.

  • 33.
    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.

  • 34.
    Gutierrez, P.J
    et al.
    Instituto de Astrofísica de Andalucía-CSIC, PO Box 3004, 18080 Granada, Spain .
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Ortiz, J.L
    Instituto de Astrofísica de Andalucía-CSIC, PO Box 3004, 18080 Granada, Spain .
    Rodrigo, R.
    Instituto de Astrofísica de Andalucía-CSIC, PO Box 3004, 18080 Granada, Spain .
    Vidal-Nunez, M.J
    Instituto de Astrofísica de Andalucía-CSIC, PO Box 3004, 18080 Granada, Spain .
    Commets on the amplitude-phase relationship of asteroid lightcurves: Effects of topography, surface scattering properties, and obliquity2006In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 454, no 1, p. 367-377Article in journal (Refereed)
    Abstract [en]

    Aims. We present a theoretical study on the amplitude-phase relationship (APR) for lightcurves of simulated asteroids.

    Methods. In support of the Rosetta (ESA) mission, we developed a numerical model for the investigation of the light reflectance properties of asteroidal bodies. The code is able to deal with irregular and chemically inhomogeneous surfaces, taking shadowing effects into account. Several standard scattering models have been implemented, which govern local reflectance properties, e. g. the Hapke model and the Lumme-Bowell model. From a kinematic standpoint, the body can move in an arbitrary orbit, and it may rotate in either pure or complex mode with an arbitrary orientation of its angular momentum. As an application of the code, we studied the dependence of the APR on several factors, such as the illumination and observational geometries, overall shape, and large-scale topography, as well as the surface characteristics represented by the parameters in the Hapke and Lumme-Bowell models.

    Results. In our study, we find that mineralogy, regolith properties, and small-scale surface roughness (i. e., characteristics embodied in the considered surface scattering models), have a negligible effect on the APR. Furthermore, large-scale topography introduces a rather significant dispersion in the APR slope, on the order of 0.010 mag deg(-1). Our simulations suggest that obliquity is the major agent for shaping the APR, causing a 0.020 mag deg(-1) dispersion in the APR slope; the larger the obliquity, the smaller the slope of the APR. For intermediate aspect angles, large obliquities could even lead to an amplitude that decreases with the phase angle.

  • 35.
    Höfner, S.
    et al.
    Max Planck Inst Sonnensyst Forsch, Goettingen; TU Braunschweig, Inst Geophys & Extraterr Phys.
    Vincent, J. -B
    Max Planck Inst Sonnensyst Forsch, Goettingen.
    Blum, J.
    TU Braunschweig, Inst Geophys & Extraterr Phys.
    Davidsson, Björn J. R.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Jet Prop Lab, Pasadena.
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    El-Maarry, M. R.
    Univ Bern, Phys Inst.
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Hofmann, M.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Hu, X.
    TU Braunschweig, Inst Geophys & Extraterr Phys.
    Pajola, M.
    Univ Padua, Dept Phys & Astron G Galilei; Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom.
    Barbieri, C.
    Univ Padua, Dept Phys & Astron G Galilei.
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM.
    Rodrigo, R.
    ESA, ESAC, Ctr Astrobiol INTA CSIC, Madrid; Int Space Sci Inst, Bern.
    Koschny, D.
    European Space Agcy, Res & Sci Support Dept, Noordwijk.
    Rickman, H.
    PAS Space Res Ctr, Warsaw.
    Keller, H. U.
    TU Braunschweig, Inst Geophys & Extraterr Phys.
    A'Hearn, M. F.
    Max Planck Inst Sonnensyst Forsch, Gottingen; Univ Maryland, Dept Astron, College Pk; Gauss Prof Akad Wissensch Gottingen.
    Auger, A. -T
    Aix Marseille Univ, CNRS, LAM.
    Barucci, M. A.
    Univ Paris 06, Univ Paris Diderot, UPMC, CNRS, LESIA, Observ Paris, Meudon.
    Bertaux, J.-L
    LATMOS, CNRS / UVSQ / IPSL, Guyancourt.
    Bertini, I.
    Univ Padua, Dept Phys & Astron G Galilei.
    Bodewits, D.
    Univ Maryland, Dept Astron.
    Cremonese, G.
    Univ Padua, Dept Phys & Astron G Galilei.
    Da Deppo, V.
    Univ Padua, Dept Phys & Astron G Galilei.
    Debei, S.
    Univ Padua, Dept Phys & Astron G Galilei.
    De Cecco, M.
    Univ Padua, Dept Phys & Astron G Galilei.
    Fornasier, S.
    Univ Paris 06, Univ Paris Diderot, UPMC, CNRS,LESIA, Observ Paris, Meudon.
    Fulle, M.
    INAF, Osservatorio Astron Trieste.
    Gicquel, A.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM.
    Gutiérrez, P. J.
    Inst Astrofis Andalucia, CSIC, Glorieta Astron, Granada.
    Gutiérrez-Marqués, P.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Güttler, C.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Hviid, S. F.
    DLR, Inst Planetary Res, Germany.
    Ip, W.-H
    Natl Cent Univ, Inst Space Sci, Chungli.
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM.
    Knollenberg, J.
    DLR, Inst Planetary Res, Berlin.
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Gottingen; Budapest Univ Technol & Econ, Dept Mech Opt & Engn Informat.
    Kramm, J. -R
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Kührt, E.
    DLR, Inst Planetary Res, Berlin.
    Küppers, M.
    ESA ESCA, Villanueva De La Canada.
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei.
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei.
    Lopez-Moreno, J. J.
    Inst Astrofis Andalucia, CSIC, Glorieta Astron, Granada 18008, Spain..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei.
    Michalik, H.
    TU Braunschweig, Inst Geophys & Extraterr Phys, Braunschweig.
    Moissl-Fraund, R.
    Univ Padua, Dept Phys & Astron G Galilei.
    Moreno, F.
    Inst Astrofis Andalucia, CSIC, Glorieta Astron, Granada.
    Mottola, S.
    DLR, Inst Planetary Res, Berlin.
    Naletto, G.
    Univ Padua, Dept Phys & Astron G Galilei; Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom; Univ Padua, Dept Informat Engn.
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Preusker, F.
    DLR, Inst Planetary Res, Berlin.
    Scholten, F.
    DLR, Inst Planetary Res, Berlin.
    Shi, X.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Thomas, N.
    Univ Bern, Phys Inst, Bern.
    Toth, I.
    Aix Marseille Univ, CNRS, LAM; Observ Hungarian Acad Sci, Budapest.
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Zitzmann, S.
    Max Planck Inst Sonnensyst Forsch, Gottingen.
    Thermophysics of fractures on comet 67P/Churyumov-Gerasimenko2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 608, article id A121Article in journal (Refereed)
    Abstract [en]

    Context. The camera OSIRIS on board Rosetta obtained high-resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko (67P). Great parts of the nucleus surface are composed of fractured terrain.

    Aims. Fracture formation, evolution, and their potential relationship to physical processes that drive activity are not yet fully understood. Observed temperatures and gas production rates can be explained or interpreted with the presence of fractures by applying appropriate modelling methods.

    Methods. We followed a transient thermophysical model approach that includes radiative, conductive, and water-ice sublimation fluxes by considering a variety of heliocentric distances, illumination conditions, and thermophysical properties for a set of characteristic fracture geometries on the nucleus of 67P. We computed diurnal temperatures, heat fluxes, and outgassing behaviour in order to derive and distinguish the influence of the mentioned parameters on fractured terrain.

    Results. Our analysis confirms that fractures, as already indicated by former studies about concavities, deviate from flat-terrain topographies with equivalent properties, mostly through the effect of self-heating. Compared to flat terrain, illuminated cometary fractures are generally warmer, with smaller diurnal temperature fluctuations. Maximum sublimation rates reach higher peaks, and dust mantle quenching effects on sublimation rates are weaker. Consequently, the rough structure of the fractured terrain leads to significantly higher inferred surface thermal inertia values than for flat areas with identical physical properties, which might explain the range of measured thermal inertia on 67P.

    Conclusions. At 3.5 AU heliocentric distance, sublimation heat sinks in fractures converge to maximum values >50 W / m2 and trigger dust activity that can be related mainly to H2O. Fractures are likely to grow through the erosive interplay of alternating sublimation and thermal fatigue.

  • 36. 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.

  • 37.
    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.

  • 38.
    Keller, H. U.
    et al.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany;TU Braunschweig, Inst Geophys & Extraterrestr Phys, D-38106 Braunschweig, Germany.
    Mottola, S.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Hviid, S. F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kuehrt, E.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Skorov, Y.
    TU Braunschweig, Inst Geophys & Extraterrestr Phys, D-38106 Braunschweig, Germany.
    Otto, K.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Vincent, J. -B
    Oklay, N.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Schroeder, S. E.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA;Univ Padua, Ctr Ateneo Studi Attivit Spaziali, Guiseppe Colombo CISAS, I-35131 Padua, Italy.
    Shi, X.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, H-1121 Budapest, Hungary.
    Preusker, F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Scholten, F.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Sierks, H.
    Max Planck Inst Sonnensyst Forschung, 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.
    UVSQ, IPSL, CNRS, LATMOS, 11 Blvd Alembert, F-78280 Guyancourt, France.
    Rodrigo, R.
    Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland;CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.
    Koschny, D.
    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.
    Rickman, H.
    European Space Agcy, Sci Support Off, NL-2201 Noordwijk, Netherlands.
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    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 Studi Attivit Spaziali, Guiseppe Colombo CISAS, I-35131 Padua, Italy.
    Cremonese, G.
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, 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 Padua, Italy.
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy.
    Deller, J.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany;Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, Obs Paris,LESIA, 5 Pl J Janssen, F-92195 Meudon, France.
    Fulle, M.
    INAF, Osservatorio Astron, 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, C Glorieta Astron S-N, E-18008 Granada, Spain.
    Guettler, C.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Hofmann, M.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Ip, W. -H
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, F-13388 Marseille, France.
    Knollenberg, J.
    Deutsches Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch Asteroiden & Kometen, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kuppers, M.
    European Space Astron Ctr, Sci Support Off, ESA, POB 78, E-28691 Madrid, Spain.
    Lara, L. -M
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron S-N, E-18008 Granada, Spain.
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy.
    Tubiana, C.
    Max Planck Inst Sonnensyst Forschung, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.
    Seasonal mass transfer on the nucleus of comet 67P/Chuyumov-Gerasimenko2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, p. S357-S371Article in journal (Refereed)
    Abstract [en]

    We collect observational evidence that supports the scheme of mass transfer on the nucleus of comet 67P/Churyumov-Gerasimenko. The obliquity of the rotation axis of 67P causes strong seasonal variations. During perihelion the southern hemisphere is four times more active than the north. Northern territories are widely covered by granular material that indicates back fall originating from the active south. Decimetre sized chunks contain water ice and their trajectories are influenced by an antisolar force instigated by sublimation. OSIRIS observations suggest that up to 20 per cent of the particles directly return to the nucleus surface taking several hours of traveltime. The back fall covered northern areas are active if illuminated but produce mainly water vapour. The decimetre chunks from the nucleus surface are too small to contain more volatile compounds such as CO2 or CO. This causes a north-south dichotomy of the composition measurements in the coma. Active particles are trapped in the gravitational minimum of Hapi during northern winter. They are 'shock frozen' and only re-activated when the comet approaches the sun after its aphelion passage. The insolation of the big cavity is enhanced by self-heating, i.e. reflection and IR radiation from the walls. This, together with the pristinity of the active back fall, explains the early observed activity of the Hapi region. Sobek may be a role model for the consolidated bottom of Hapi. Mass transfer in the case of 67P strongly influences the evolution of the nucleus and the interpretation of coma measurements.

  • 39.
    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.

  • 40. Koschny, D
    et al.
    Dhiri, V
    Wirth, K
    Zender, J
    Solaz, R
    Hoofs, R
    Laureijs, R
    Ho, T.-M.
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Schwehm, G
    Scientific planning and commanding of the Rosetta payload2007In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 128, no 1-4, p. 167-188Article in journal (Refereed)
    Abstract [en]

    ESA’s Rosetta mission was launched in March 2004 and is on its way to comet 67P/Churyumov-Gerasimenko, where it is scheduled to arrive in summer 2014. It comprises a payload of 12 scientific instruments and a Lander. All instruments are provided by Principal Investigators, which are responsible for their operations.

    As for most ESA science missions, the ground segment of the mission consists of a Mission Operations Centre (MOC) and a Science Operations Centre (SOC). While the MOC is responsible for all spacecraft-related aspects and the final uplink of all command timelines to the spacecraft, the scientific operations of the instruments and the collection of the data and ingestion into the Planetary Science Archive are coordinated by the SOC. This paper focuses on the tasks of the SOC and in particular on the methodology and constraints to convert the scientific goals of the Rosetta mission to operational timelines.

  • 41.
    La Forgia, F.
    et al.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35122 Padua, Italy..
    Giacomini, L.
    Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy..
    Lazzarin, M.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35122 Padua, Italy..
    Massironi, M.
    Univ Padua, Dipartimento Geosci, I-35131 Padua, Italy..
    Oklay, N.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Scholten, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Pajola, M.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Bertini, I.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Barbieri, C.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35122 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Naletto, G.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy.;Univ Padua, Dept Informat Engn, I-35131 Padua, Italy.;CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Simioni, E.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Preusker, F.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Lamy, P.
    CNRS, UMR 7236, 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. 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..
    Auger, A. -T
    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, France..
    Bertaux, J. -L
    Besse, S.
    European Space Res & Technol Ctr ESA, Sci Support Off, NL-2201 AZ Noordwijk, Netherlands..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Da Deppo, V.
    CNR IFN UOS Padova LUXOR, I-35131 Padua, Italy..
    Davidsson, Björn
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, I-38123 Trento, Italy..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    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, France.;Univ Paris Diderot, Sorbonne Paris Cite, F-75205 Paris 13, France..
    Fulle, M.
    INAF Osservatorio Astron Trieste, I-34014 Trieste, Italy..
    Groussin, O.
    CNRS, UMR 7236, Lab Astrophys Marseille, F-13388 Marseille 13, France.;Aix Marseille Univ, F-13388 Marseille 13, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hall, I.
    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 7236, 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..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    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..
    Lara, L. -M
    Lopez Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Magrin, S.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35122 Padua, Italy..
    Marzari, F.
    Univ Padua, Dipartimento Fis & Astron G Galilei, I-35122 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Datentech & Kommunikat Netze, D-38106 Braunschweig, Germany..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, D-12489 Berlin, Germany..
    Pommerol, A.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Geomorphology and spectrophotometry of Philae's landing site on comet 67P/Churyumov-Gerasimenko2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A41Article in journal (Refereed)
    Abstract [en]

    Context. On 12 November 2014 the European mission Rosetta succeeded in delivering a lander, named Philae, on the surface of one of the smallest, low-gravity and most primitive bodies of the solar system, the comet 67P/Churyumov-Gerasimenko (67P). Aims. The aim of this paper is to provide a comprehensive geomorphological and spectrophotometric analysis of Philae's landing site (Agilkia) to give an essential framework for the interpretation of its in situ measurements. Methods. OSIRIS images, coupled with gravitational slopes derived from the 3D shape model based on stereo-photogrammetry were used to interpret the geomorphology of the site. We adopted the Hapke model, using previously derived parameters, to photometrically correct the images in orange filter (649.2 nm). The best approximation to the Hapke model, given by the Akimov parameter-less function, was used to correct the reflectance for the effects of viewing and illumination conditions in the other filters. Spectral analyses on coregistered color cubes were used to retrieve spectrophotometric properties. Results. The landing site shows an average normal albedo of 6.7% in the orange filter with variations of similar to 15% and a global featureless spectrum with an average red spectral slope of 15.2%/100 nm between 480.7 nm (blue filter) and 882.1 nm (near-IR filter). The spatial analysis shows a well-established correlation between the geomorphological units and the photometric characteristics of the surface. In particular, smooth deposits have the highest reflectance a bluer spectrum than the outcropping material across the area. Conclusions. The featureless spectrum and the redness of the material are compatible with the results by other instruments that have suggested an organic composition. The observed small spectral variegation could be due to grain size effects. However, the combination of photometric and spectral variegation suggests that a compositional differentiation is more likely. This might be tentatively interpreted as the effect of the efficient dust-transport processes acting on 67P. High-activity regions might be the original sources for smooth fine-grained materials that then covered Agilkia as a consequence of airfall of residual material. More observations performed by OSIRIS as the comet approaches the Sun would help interpreting the processes that work at shaping the landing site and the overall nucleus.

  • 42.
    Lai, Ian-Lin
    et al.
    Natl Cent Univ, Inst Space Sci, 300 Zhongda Rd, Taoyuan 32001, Taiwan..
    Ip, Wing-Huen
    Natl Cent Univ, Inst Space Sci, 300 Zhongda Rd, Taoyuan 32001, Taiwan.;Natl Cent Univ, Inst Astron, 300 Zhongda Rd, Taoyuan 32001, Taiwan.;Macau Univ Sci & Technol, Space Sci Inst, Taipa, Macau, Peoples R China..
    Su, Cheng-Chin
    Natl Chiao Tung Univ, Dept Mech Engn, 1001 Univ Rd, Hsinchu 300, Taiwan..
    Wu, Jong-Shinn
    Natl Chiao Tung Univ, Dept Mech Engn, 1001 Univ Rd, Hsinchu 300, Taiwan..
    Lee, Jui-Chi
    Natl Cent Univ, Dept Earth Sci, 300 Zhongda Rd, Taoyuan 32001, Taiwan..
    Lin, Zhong-Yi
    Natl Cent Univ, Inst Astron, 300 Zhongda Rd, Taoyuan 32001, Taiwan..
    Liao, Ying
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Thomas, Nicolas
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Sierks, Holger
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, Cesare
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, Philippe
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France..
    Rodrigo, Rafael
    CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, Detlef
    ESA, European Space Res & Technol Ctr, Sci Support Off, Keplerlaan 1,Postbus 299, NL-2201 AG 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, Horst Uwe
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Agarwal, Jessica
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, Michael 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, Gottingen, Germany..
    Barucci, Maria Antonella
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, Jean-Loup
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Bertini, Ivano
    Univ Padua, CISAS, Ctr Studies & Act Space G Colombo, Padua, Italy..
    Boudreault, Steven
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Cremonese, Gabriele
    INAF, Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, Vania
    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, Stefano
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, Mariolino
    Univ Trento, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, Jakob
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fornasier, Sonia
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA,Observ Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, Marco
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, Olivier
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France..
    Gutierrez, Pedro J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Guttler, Carsten
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Hofmann, Marc
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, Stubbe F.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Jorda, Laurent
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France..
    Knollenberg, J. Org
    Kovacs, Gabor
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -Rainer
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kuhrt, Ekkehard
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planeten Forsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, Michael
    ESA, European Space Astron Ctr, Operat Dept, POB 78, E-28691 Madrid, Spain..
    Lara, Luisa M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Lazzarin, Monica
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Moreno, Jose J. Lopez
    Marzari, Francesco
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Naletto, Giampiero
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, Nilda
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Shi, Xian
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Tubiana, Cecilia
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, Jean-Baptiste
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
    Gas outflow and dust transport of comet 67P/Churyumov-Gerasimenko2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S533-S546Article in journal (Refereed)
    Abstract [en]

    Because of the diurnal thermal cycle and the irregular shape of the nucleus, gas outflow of comet 67P/Churyumov-Gerasimenko could be highly anisotropic as indicated by the colliminated dust jet structures on the sunlit side. Based on the OSIRIS imaging observations of the outgassing effect, a simple model of surface sublimation can be constructed by taking into account the dependence on the solar insolation. With preliminary information on the time variability of the global gas production rate, a sequence of gas coma models can be generated at different epochs before and after perihelion. We also investigate different patterns of dust particle dynamics under the influences of nuclear rotation and gas drag. From these considerations, a consistent picture of the spatial distribution of dusty materials across the surface of comet 67P as it moves around the perihelion can be developed. It is found that because of the redeposition of the ejected dust from the Southern hemisphere to the Northern hemisphere during the southern summer season the Hapi region could gain up to 0.4 m while the Wosret region would lose up to 1.8 m of dust mantle per orbit.

  • 43.
    Lai, I-L
    et al.
    Natl Cent Univ, Grad Inst Space Sci, Taoyuan 32001, Taiwan.
    Ip, W-H
    Natl Cent Univ, Grad Inst Space Sci, Taoyuan 32001, Taiwan;Natl Cent Univ, Inst Astron, Taoyuan 32001, Taiwan;Macau Univ Sci & Technol, Space Sci Inst, Macau, Peoples R China.
    Lee, J-C
    Natl Cent Univ, Dept Earth Sci, Taoyuan 32001, Taiwan.
    Lin, Z. Y.
    Natl Cent Univ, Inst Astron, Taoyuan 32001, Taiwan.
    Vincent, J-B
    German Aerosp Ctr DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany.
    Oklay, N.
    German Aerosp Ctr DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, 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.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, 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 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, Bartycka 18A, PL-00716 Warsaw, Poland.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Barucci, M. A.
    Univ Paris Diderot, LESIA Observ Paris, CNRS, Univ Pierre & Marie Curie, 5 Pl J Janssen, F-92195 Meudon, France.
    Bertaux, J-L
    CNR IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy.
    Bertini, I
    Univ Padua, Ctr Studies & Act Space G Colombo, CISAS G Colombo, Padua, Italy.
    Bodewits, D.
    Auburn Univ, Dept Phys, Auburn, AL 36849 USA.
    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, 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 Mesiano 77, I-38100 Trento, Italy.
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Fornasier, S.
    Univ Paris Diderot, LESIA Observ Paris, CNRS, Univ Pierre & Marie Curie, 5 Pl J Janssen, F-92195 Meudon, France.
    Fulle, M.
    INAF, Osservatorio Astron, Via Tiepolo 11, I-34014 Trieste, Italy.
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Güttler, 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.
    German Aerosp Ctr DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany.
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France.
    Knollenberg, J.
    German Aerosp Ctr 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.
    Kramm, J-R
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kührt, E.
    German Aerosp Ctr DLR, Inst Planetary Res, Rutherfordstr 2, D-12489 Berlin, Germany.
    Küppers, M.
    European Space Astron Ctr ESA, Operat Dept, Pob 78, Madrid 28691, Spain.
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain.
    Marzari, F.
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy.
    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.
    Thomas, N.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.
    Seasonal variations in source regions of the dust jets on comet 67P/Churyumov-Gerasimenko2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A17Article in journal (Refereed)
    Abstract [en]

    Aims: We investigate the surface distribution of the source regions of dust jets on comet 67P/Churyumov-Gerasimenko as a function of time.

    Methods: The dust jet source regions were traced by the comprehensive imaging data set provided by the OSIRIS scientific camera.

    Results: We show in detail how the projected footpoints of the dust jets and hence the outgassing zone would move in consonance with the sunlit belt. Furthermore, a number of source regions characterized by repeated jet activity might be the result of local topographical variations or compositional heterogeneities.

    Conclusions: The spatial and temporal variations in source regions of the dust jets are influenced significantly by the seasonal effect. The strong dependence on the solar zenith angle and local time could be related to the gas sublimation process driven by solar insolation on a surface layer of low thermal inertia.

  • 44. Lamy, P
    et al.
    Toth, I
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Groussin, O
    Gutierrez, P
    Jorda, L
    Kaasalainen, M
    Lowry, S
    A portrait of the nucleus of Comet 67P/Churyumov-Gerasimenko2007In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 128, no 1-4, p. 23-66Article in journal (Refereed)
    Abstract [en]

    In 2003, comet 67P/Churyumov–Gerasimenko was selected as the new target of the Rosetta mission as the most suitable alternative to the original target, comet 46P/Wirtanen, on the basis of orbital considerations even though very little was known about the physical properties of its nucleus. In a matter of a few years and based on highly focused observational campaigns as well as thorough theoretical investigations, a detailed portrait of this nucleus has been established that will serve as a baseline for planning the Rosetta operations and observations. In this review article, we present a novel method to determine the size and shape of a cometary nucleus: several visible light curves were inverted to produce a size–scale free three–dimensional shape, the size scaling being imposed by a thermal light curve. The procedure converges to two solutions which are only marginally different. The nucleus of comet 67P/Churyumov–Gerasimenko emerges as an irregular body with an effective radius (that of the sphere having the same volume) = 1.72 km and moderate axial ratios a/b = 1.26 and a/c = 1.5 to 1.6. The overall dimensions measured along the principal axis for the two solutions are 4.49–4.75 km, 3.54–3.77 km and 2.94–2.92 km. The nucleus is found to be in principal axis rotation with a period = 12.4–12.7 h. Merging all observational constraints allow us to specify two regions for the direction of the rotational axis of the nucleus: RA = 220°+50° −30° and Dec = −70° ± 10° (retrograde rotation) or RA = 40°+50° -30° and Dec = +70°± 10° (prograde), the better convergence of the various determinations presently favoring the first solution. The phase function, although constrained by only two data points, exhibits a strong opposition effect rather similar to that of comet 9P/Tempel 1. The definition of the disk–integrated albedo of an irregular body having a strong opposition effect raises problems, and the various alternatives led to a R-band geometric albedo in the range 0.045–0.060, consistent with our present knowledge of cometary nuclei. The active fraction is low, not exceeding ~ 7% at perihelion, and is probably limited to one or two active regions subjected to a strong seasonal effect, a picture coherent with the asymmetric behaviour of the coma. Our slightly downward revision of the size of the nucleus of comet 67P/Churyumov-Gerasimenko resulting from the present analysis (with the correlative increase of the albedo compared to the originally assumed value of 0.04), and our best estimate of the bulk density of 370 kg m−3, lead to a mass of ~ 8 × 10e12 kg which should ease the landing of Philae and insure the overall success of the Rosetta mission.

  • 45.
    Lara, L. M.
    et al.
    Inst Astrofis Andalucia CSIC, Glorieta Astron, Granada 18008, Spain..
    Lowry, S.
    Univ Kent, Ctr Astrophys & Planetary Sci, Sch Phys Sci, Canterbury CT2 7NH, Kent, England..
    Vincent, J. -B
    Gutierrez, P. J.
    Inst Astrofis Andalucia CSIC, Glorieta Astron, Granada 18008, Spain..
    Rozek, A.
    Univ Kent, Ctr Astrophys & Planetary Sci, Sch Phys Sci, Canterbury CT2 7NH, Kent, England..
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Oklay, N.
    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 G Galilei, I-35122 Padua, Italy.;Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Rodrigo, R.
    European Space Astron Ctr, European Space Agcy, Ctr Astrobiol INTA CSIC, Madrid 28691, 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..
    Auger, A. -T
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    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, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, Italy..
    Besse, S.
    European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35122 Padua, Italy..
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Da Deppo, V.
    CNR IFN UOS 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..
    El-Maarry, M. R.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Ferri, F.
    Univ Padua, Ctr Studies & Act Space CISAS G Colombo, I-35131 Padua, 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..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, France..
    Gutierrez-Marques, P.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    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.
    Aix Marseille Univ, CNRS, UMR 7326, Lab Astrophys Marseille, F-13388 Marseille, 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.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    Lazzarin, M.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Lin, Z. -Y
    Lopez-Moreno, J. J.
    Inst Astrofis Andalucia CSIC, Glorieta Astron, Granada 18008, Spain..
    Magrin, S.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, I-35122 Padua, Italy..
    Michalik, H.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, D-38106 Braunschweig, Germany..
    Moissl-Fraund, R.
    ESA ESAC, Villanueva De La Canada 28691, Spain..
    Moreno, F.
    Inst Astrofis Andalucia CSIC, Glorieta Astron, Granada 18008, Spain..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, 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..
    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..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Sabau, M. D.
    Inst Nacl Tecn Aeroespacial, Madrid 28850, Spain..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Large-scale dust jets in the coma of 67P/Churyumov-Gerasimenko as seen by the OSIRIS instrument onboard Rosetta2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A9Article in journal (Refereed)
    Abstract [en]

    Context. During the most recent perihelion passage in 2009 of comet 67P/Churyumov-Gerasimenko (67P), ground-based observations showed an anisotropic dust coma where jet-like features were detected at similar to 1.3 AU from the Sun. The current perihelion passage is exceptional as the Rosetta spacecraft is monitoring the nucleus activity since March 2014, when a clear dust coma was already surrounding the nucleus at 4.3 AU from the Sun. Subsequently, the OSIRIS camera also witnessed an outburst in activity between April 27 and 30, and since mid-July, the dust coma at rh similar to 3.7-3.6 AU preperihelion is clearly non-isotropic, pointing to the existence of dust jet-like features. Aims. We aim to ascertain on the nucleus surface the origin of the dust jet-like features detected as early as in mid-July 2014. This will help to establish how the localized comet nucleus activity compares with that seen in previous apparitions and will also help following its evolution as the comet approaches its perihelion, at which phase most of the jets were detected from ground-based observations. Determining these areas also allows locating them in regions on the nucleus with spectroscopic or geomorphological distinct characteristics. Methods. Three series of dust images of comet 67P obtained with the Wide Angle Camera (WAC) of the OSIRIS instrument onboard the Rosetta spacecraft were processed with different enhancement techniques. This was made to clearly show the existence of jet-like features in the dust coma, whose appearance toward the observer changed as a result of the rotation of the comet nucleus and of the changing observing geometry from the spacecraft. The position angles of these features in the coma together with information on the observing geometry, nucleus shape, and rotation, allowed us to determine the most likely locations on the nucleus surface where the jets originate from. Results. Geometrical tracing of jet sources indicates that the activity of the nucleus of 67P gave rise during July and August 2014 to large-scale jet-like features from the Hapi, Hathor, Anuket, and Aten regions, confirming that active regions may be present on the nucleus localized at 60. northern latitude as deduced from previous comet apparitions. There are also hints that large-scale jets observed from the ground are possibly composed, at their place of origin on the nucleus surface, of numerous small-scale features.

  • 46.
    Lee, Jui-Chi
    et al.
    Natl Cent Univ, Dept Earth Sci, 300 Chung Rd, Chungli 32054, Taiwan..
    Massironi, Matteo
    Univ Padua, Dept Geosci, Via G Gradenigo 6, I-35131 Padua, Italy.;Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Ip, Wing-Huen
    Natl Cent Univ, Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan.;Natl Cent Univ, Inst Space Sci, 300 Chung Da Rd, Chungli 32054, Taiwan.;Macau Univ Sci & Technol, Space Sci Inst, Ave Wai Long, Taipa, Macao, Peoples R China..
    Giacomini, Lorenza
    Univ Padua, Dept Geosci, Via G Gradenigo 6, I-35131 Padua, Italy..
    Ferrari, Sabrina
    Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Penasa, Luca
    Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    El-Maarry, Mohamed Ramy
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Pajola, Maurizio
    Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy.;NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Lai, Ian-Lin
    Natl Cent Univ, Inst Space Sci, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Lin, Zhong-Yi
    Natl Cent Univ, Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Ferri, Francesca
    Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Sierks, Holger
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Barbieri, Cesare
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, Philippe
    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, Rafael
    CSIC, INTA, Ctr Astrobiol, E-28850 Madrid, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, Detlef
    Sci Support Off, European Space Res & Technol Ctr ESA, Keplerlaan 1,Postbus 299, NL-2201AZ 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, Poland.
    Keller, Horst Uwe
    Tech Univ Carolo Wilhelmina Braunschweig, IGEP, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Agarwal, Jessica
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    A'Hearn, Michael 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 Geschaftsstelle, Theaterstr 7, D-37073 Gottingen, Niedersachsen, Germany..
    Barucci, Maria Antonella
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA,Observatoire Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, Jean-Loup
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA,Observatoire Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertini, Ivano
    Univ Padua, CISAS, Ctr Studies & Activ Space G Colombo, Via Venezia 15, I-35131 Padua, Italy..
    Cremonese, Gabriele
    Osserv Astron Padova, INAF, Vicolo Osservatorio 5, I-35122 Padua, Italy..
    Da Deppo, Vania
    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, Stefano
    Univ Padua, Dept Ind Engn, Via Venezia 1, I-35131 Padua, Italy..
    De Cecco, Mariolino
    Univ Trent, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, Jakob
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Fornasier, Sonia
    Univ Paris Diderot, Univ Pierre & Marie Curie, CNRS, LESIA,Observatoire Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, Marco
    Osserv Astron Trieste, INAF, Via Tiepolo 11, I-34014 Trieste, Italy..
    Groussin, Olivier
    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..
    Gutierrez, Pedro J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Guettler, Carsten
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hofmann, Marc
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Hviid, Stubbe F.
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany.;Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Jorda, Laurent
    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, Joerg
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kovacs, Gabor
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kramm, J. -Rainer
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Kuehrt, Ekkehard
    Inst Planetenforsch, Deutsch Zentrum Luft & Raumfahrt DLR, Rutherfordstr 2, D-12489 Berlin, Germany..
    Kuppers, Michael
    European Space Astron Ctr ESA, Operat Dept, POB 78, E-28691 Madrid, Spain..
    Lara, Luisa M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Lazzarin, Monica
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Marzari, Francesco
    Univ Padua, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lopez Moreno, Jose J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astron, E-18008 Granada, Spain..
    Naletto, Giampiero
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy..
    Oklay, Nilda
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Shi, Xian
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Thomas, Nicolas
    Natl Cent Univ, Inst Astron, 300 Chung Da Rd, Chungli 32054, Taiwan..
    Tubiana, Cecilia
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Vincent, Jean-Baptiste
    Max Planck Inst Sonnensyst Forsch, Justus Von Liebig Weg 3, D-37077 Gottingen, Germany..
    Geomorphological mapping of comet 67P/Churyumov-Gerasimenko's Southern hemisphere2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S573-S592Article in journal (Refereed)
    Abstract [en]

    In 2015 May, the Southern hemisphere of comet 67P/Churyumov-Gerasimenko became visible by the OSIRIS cameras on-board the Rosetta spacecraft. The resolution was high enough to carry out a detailed analysis of the surface morphology, which is quite different from the Northern hemisphere. Previous works show that fine particle deposits are the most extensive geological unit in the Northern hemisphere. In contrast, the Southern hemisphere is dominated by outcropping consolidated terrain. In this work, we provide geomorphological maps of the Southern hemisphere with the distinction of both geological units and linear features. The geomorphological maps described in this study allow us to gain a better understanding of the processes shaping the comet nucleus and the distribution of primary structures such as fractures and strata.

  • 47. Lee, Seungwon
    et al.
    von Allmen, Paul
    Kamp, Lucas
    Gulkis, Samuel
    Davidsson, Björn
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Non-LTE radiative transfer for sub-millimeter water lines in Comet 67P/Churyumov-Gerasimenko2011In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 215, no 2, p. 721-731Article in journal (Refereed)
    Abstract [en]

    The European Space Agency (ESA) Rosetta spacecraft (Schulz, R., Alexander, C., Boehnhardt, H., Glassmeier, K.H. (Eds.) [2009]. "ROSETTA - ESA") will encounter Comet 67P/Churyumov-Gerasimenko in 2014 and spend the next 18 months in the vicinity of the comet, permitting very high spatial and spectral resolution observations of the coma and nucleus. During this time, the heliocentric distance of the comet will change from similar to 3.5 AU to similar to 1.3 AU, accompanied by an increasing temperature of the nucleus and the development of the coma. The Microwave Instrument for the Rosetta Orbiter (MIRO) will observe the ground-state rotational transition (1(10)-1(01)) of H(2) (16)O at 556.936 GHz, the two isotopologues H(2)(17)O and H(2) (18)O and other molecular transitions in the coma during this time (Gulkis, S. et al., [2007]. MIRO: Microwave Instrument for Rosetta Orbiter. Space Sci. Rev, 128, 561-597).

    The aim of this study is to simulate the water line spectra that could be obtained with the MIRO instrument and to understand how the observed line spectra with various viewing geometries can be used to study the physical conditions of the coma and the water excitation processes throughout the coma. We applied an accelerated Monte Carlo method to compute the excitations of the seven lowest rotational levels (1(01), 1(10), 2(12), 2(21), 3(03), 3(12), and 3(21)) of ortho-water using a comet model with spherically symmetric water outgassing, density, temperature and expansion velocity at three different heliocentric distances 1.3 AU, 2.5 AU, and 3.5 AU. Mechanisms for the water excitation include water-water collisions, water-electron collisions, and infrared pumping by solar radiation.

    Synthetic line spectra are calculated at various observational locations and directions using the MIRO instrument parameters. We show that observations at varying viewing distances from the nucleus and directions have the potential to give diagnostic information on the continuum temperature and water outgassing rates at the surface of the nucleus, and the gas density, expansion velocity, and temperature of the coma as a function of distance from the nucleus. The gas expansion velocity and temperature affect the spectral line width and frequency shift of the line from the rest frequency, while the gas density (which is directly related to the outgassing rate) and the line excitation temperature determine the antenna temperature of the absorption and emission signal in the line profile.

  • 48. Lin, Z. -Y
    et al.
    Ip, W. -H
    Lai, I. -L
    Lee, J. -C
    Vincent, J. -B
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    Bodewits, D.
    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 G Galilei, I-35122 Padua, Italy.;Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Rodrigo, R.
    European Space Astron Ctr ESAC, European Space Agcy ESA, Ctr Astrobiol INTA CSIC, Madrid 28691, 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, IGEP, 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, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Cremonese, G.
    INAF Osservatorio Astron Padova, I-35121 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, I-38123 Trento, Italy..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Observ Paris, F-92195 Meudon, France..
    Fuelle, M.
    Osserv Astron Trieste, INAF, I-34143 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, E-18008 Granada, Spain..
    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..
    Jorda, L.
    Aix Marseille Univ, CNRS, UMR 7326, LAM, F-13388 Marseille, 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 ESAC, European Space Agcy ESA, Ctr Astrobiol INTA CSIC, Madrid 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-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, 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, D-12489 Berlin, Germany..
    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 & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Rozek, A.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, I-35131 Padua, Italy..
    Thomas, N.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Liao, Y.
    Univ Bern, Inst Phys, CH-3012 Bern, Switzerland..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Morphology and dynamics of the jets of comet 67P/Churyumov-Gerasimenko: Early-phase development2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 583, article id A11Article in journal (Refereed)
    Abstract [en]

    Aims. The OSIRIS camera onboard the Rosetta spacecraft obtained close-up views of the dust coma of comet 67P. The jet structures can be used to trace their source regions and to examine the possible effect of gas-surface interaction. Methods. We analyzed the wide-angle images obtained in the special dust observation sequences between August and September 2014. The jet features detected in different images were compared to study their time variability. The locations of the potential source regions of some of the jets are identified by ray tracing. We used a ring-masking technique to calculate the brightness distribution of dust jets along the projected distance. Results. The jets detected between August and September 2014 mostly originated in the Hapi region. Morphological changes appeared over a timescale of several days in September. The brightness slope of the dust jets is much steeper than the background coma. This might be related to the sublimation or fragmentation of the emitted dust grains. Interaction of the expanding gas flow with the cliff walls on both sides of Hapi could lead to erosion and material down-fall to the nucleus surface.

  • 49. Lin, Z. -Y
    et al.
    Lai, I. -L
    Su, C. -C
    Ip, W. -H
    Lees, J. -C
    Wu, J. -S
    Vincent, J. -B
    La Forgia, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 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 G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.;Univ Padua, Ctr Ateneo Studied Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Lamy, P. L.
    Aix Marseille Univ, CNRS, LAM Lab Astrophys Marseille, UMR 7326, F-13388 Marseille, France..
    Rodrigo, R.
    ESAC, ESA, Ctr Astrobiol INTA CSIC, Villanueva Canada, POB 78, Madrid 28691, 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, H.
    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, LESIA Observ Paris, CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Ctr Ateneo Studied Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Cremonese, G.
    INAF Osservatorio Astron Padova, Vic 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 Trent, Via Sommarive 9, I-38123 Trento, Italy..
    Fornasier, S.
    CNRS UVSQ IPSL, LATMOS, 11 Blvd Alembert, F-78280 Guyancourt, France..
    Fulle, M.
    INAF, Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM Lab Astrophys Marseille, UMR 7326, F-13388 Marseille, France..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron, 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 Lab Astrophys Marseille, 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.
    Kueppers, M.
    ESAC, ESA, Ctr Astrobiol INTA CSIC, Villanueva Canada, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron, Granada 18008, 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, C Glorieta Astron, Granada 18008, 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..
    Michalik, H.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Mottola, S.
    Deutsch Zentrum Luft & Raumfahrt DLR, Inst Planetenforsch, Rutherfordstr 2, D-12489 Berlin, Germany..
    Naletto, G.
    Univ Padua, Ctr Ateneo Studied 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 Studied Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy..
    Rozek, A.
    Univ Padua, Ctr Ateneo Studied Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, 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..
    Observations and analysis of a curved jet in the coma of comet 67P/Churyumov-Gerasimenko2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 588, article id L3Article in journal (Refereed)
    Abstract [en]

    Aims. We analyze the physical properties and dynamical origin of a curved jet of comet 67P/Churyumov-Gerasimenko that was observed repeatedly in several nucleus rotations starting on May 30 and persisting until early August, 2015. Methods. We simulated the motion of dust grains ejected from the nucleus surface under the influence of the gravity and viscous drag e ff ect of the expanding gas flow from the rotating nucleus. Results. The formation of the curved jet is a combination of the size of the dust particles (similar to 0.1-1 mm) and the location of the source region near the nucleus equator. This enhances the spiral feature of the collimated dust stream after the dust is accelerated to a terminal speed on the order of m s(-1).

  • 50.
    Lin, Zhong-Yi
    et al.
    Natl Cent Univ, Inst Astron, Chungli 32054, Taiwan.
    Knollenberg, J.
    Inst Planetenforsch, Deuisch Zentrum Luft & Raumfahri DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Vincent, J. -B
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Ip, W-H
    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.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France.
    Rodrigo, R.
    CSIC, INTA, Ctr Astrobiol, ESA,ESAC, POB 78,E 8691, Madrid, Spain;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland.
    Koschny, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA;European Space Agcy, Res & Sci Support Dept, NL-2201 Noordwijk, Netherlands.
    Rickman, H.
    PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland.
    Keller, H. U.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys IGEP, D-38106 Braunschweig, Germany.
    Mottola, S.
    Inst Planetenforsch, Deuisch Zentrum Luft & Raumfahri DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Bodewits, D.
    Agarwal, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Barucci, M. A.
    Univ Paris Diderot, LESIA Observ Paris, CNRS, UPMC Univ Paris 06, 5 Pl J Janssen, F-92195 Meudon, France.
    Bertaux, J. -L
    Bertini, I.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Cremonese, G.
    INAF, Osservatorio Astron Padova, Vic Osservatorio 5, I-35122 Padua, Italy.
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    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 Sommarive 9, I-38123 Trento, Italy.
    Fornasier, S.
    Univ Paris Diderot, LESIA Observ Paris, CNRS, UPMC Univ Paris 06, 5 Pl J Janssen, F-92195 Meudon, France.
    Fulle, M.
    INAF, Osservatorio Astron Trieste, Via Tiepolo 11, I-34143 Trieste, Italy.
    Groussin, O.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France.
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron, 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.
    Inst Planetenforsch, Deuisch Zentrum Luft & Raumfahri DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Jorda, L.
    CNRS, Lab Astrophys Marseille, UMR 7326, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France;Aix Marseille Univ, 38 Rue Frederic Joliot Curie, F-13388 Marseille, France.
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Kramm, J. -R
    Kuehrt, E.
    Inst Planetenforsch, Deuisch Zentrum Luft & Raumfahri DLR, Rutherfordstr 2, D-12489 Berlin, Germany.
    Kuppers, M.
    CSIC, INTA, Ctr Astrobiol, ESA,ESAC, POB 78,E 8691, Madrid, Spain.
    Lai, I. -L
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron, E-18008 Granada, Spain.
    Lazzarin, M.
    Univ Padua, Ctr Ateneo Studi & Attivita Spaziali Giuseppe Col, Via Venezia 15, I-35131 Padua, Italy.
    Lee, J-C
    Lopez-Moreno, J. J.
    CSIC, Inst Astrofis Andalucia, C Glorieta Astron, E-18008 Granada, Spain.
    Marzari, F.
    Univ Padua, Dept Phys & Astron G Galilei, Vic Osservatorio 3, I-35122 Padua, Italy.
    Naletto, G.
    Univ Padua, Dept Informat Engn, Via Gradenigo 6-B, I-35131 Padua, Italy.
    Oklay, N.
    Inst Planetenforsch, Deuisch Zentrum Luft & Raumfahri DLR, Rutherfordstr 2, D-12489 Berlin, Germany;Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Ott, T.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 114, D-26111 Oldenburg, Germany.
    Drolshagen, E.
    Carl von Ossietzky Univ Oldenburg, Ammerlander Heerstr 114, D-26111 Oldenburg, 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.
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany.
    Investigating the physical properties of outbursts on comet 67P/Churyumov-Gerasimenko2017In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 469, p. S731-S740Article in journal (Refereed)
    Abstract [en]

    Cometary outbursts on several comets have been observed both by ground-based telescopes and by in situ instruments on spacecraft. However, the mechanism behind these phenomena and their physical properties are still unclear. The optical, spectrocopic and infrared remote imaging system (OSIRIS) onboard the Rosetta spacecraft provided first-hand information on the outbursts from comet 67P/Churyumov-Gerasimenko during its perihelion passage in 2015. The physical properties of the outbursts can be investigated by examining the time series of these high-resolution images. An analysis is made of the wide- and narrow-angle images obtained during the monitoring of the outburst sequences, which occurred between July and September in 2015. A ring-masking technique is used to calculate the excess brightness of the outbursts. The ejected mass and expansion velocity of the outbursts is estimated from differences in images made with the same filter (orange filter). The calculated excess brightness from these outburst plumes ranges from a few per cent to 28 per cent. In some major outbursts, the brightness contribution from the outburst plume can be one or two times higher than that of the typical coma jet activities. The strongest event was the perihelion outburst detected just a few hours before perihelion. The mass ejection rate during a generic outburst could reach a few per cent of the steady-state value of the dust coma. Transient events are detected by studying the brightness slope of the outburst plume with continuous streams of outflowing gas and dust triggered by driving mechanisms, as yet not understood, which remain active for several minutes to less than a few hours.

12 1 - 50 of 72
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