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  • 1.
    Adibekyan, V.
    et al.
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Oporto, Portugal..
    Delgado-Mena, E.
    Univ Porto, Inst Astrofis & Ciencias Espaco, CAUP, Rua Estrelas, P-4150762 Oporto, Portugal..
    Feltzing, S.
    Lund Observ, Dept Astron & Theoret Phys, Lund, Sweden..
    Gonzalez Hernandez, J. I.
    Inst Astrofis Canarias, Tenerife, Spain.;Univ La Laguna, Dept Astrofis, Tenerife, Spain..
    Hinkel, N. R.
    Arizona State Univ, Sch Earth & Space Explorat, Tempe, AZ USA.;Vanderbilt Univ, Dept Phys & Astron, Nashville, TN 37235 USA..
    Korn, Andreas J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden..
    Asplund, M.
    Australian Natl Univ, Res Sch Astron & Astrophys, Weston, ACT, Australia..
    Beck, P. G.
    Univ Paris Diderot, Ctr Saclay, Lab AIM, CEA,DRF,CNRS,IRFU,SAp, Gif Sur Yvette, France..
    Deal, M.
    Univ Montpellier, CNRS, LUPM, UMR 5299, Montpellier, France.;CNRS, IRAP, Toulouse, France..
    Gustafsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. NORDITA, Stockholm, Sweden..
    Honda, S.
    Univ Hyogo, Ctr Astron, Nishi Harima Astron Observ, Sayo, Hyogo, Japan..
    Lind, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Max Planck Inst Astron, Heidelberg, Germany..
    Nissen, P. E.
    Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Aarhus C, Denmark..
    Spina, L.
    Univ Sao Paulo, Dept Astron IAG, Sao Paulo, Brazil..
    Sun-like stars unlike the Sun: Clues for chemical anomalies of cool stars2017In: Astronomical Notes - Astronomische Nachrichten, ISSN 0004-6337, E-ISSN 1521-3994, Vol. 338, no 4, p. 442-452Article in journal (Refereed)
    Abstract [en]

    We present a summary of the splinter session Sun-like stars unlike the Sun that was held on June 9, 2016, as part of the Cool Stars 19 conference (Uppsala, Sweden), in which the main limitations (in the theory and observations) in the derivation of very precise stellar parameters and chemical abundances of Sun-like stars were discussed. The most important and most debated processes that can produce chemical peculiarities in solar-type stars were outlined and discussed. Finally, in an open discussion between all the participants, we tried to identify new pathways and prospects toward future solutions of the currently open questions.

  • 2. Adén, D.
    et al.
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Feltzing, S.
    Grebel, E. K.
    Koch, A.
    Wilkinson, M. I.
    An abundance study of red-giant-branch stars in the Hercules dwarf spheroidal galaxy2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 525, p. A153-Article in journal (Refereed)
    Abstract [en]

    Context. Dwarf spheroidal galaxies are some of the most metal-poor, and least luminous objects known. Detailed elemental abundance analysis of stars in these faint objects is key to our understanding of star formation and chemical enrichment in the early universe, and may provide useful information on how larger galaxies form. Aims. Our aim is to provide a determination of [Fe/H] and [Ca/H] for confirmed red-giant branch member stars of the Hercules dwarf spheroidal galaxy. Based on this we explore the ages of the prevailing stellar populations in Hercules, and the enrichment history from supernovae. Additionally, we aim to provide a new simple metallicity calibration for Stromgren photometry for metal-poor, red giant branch stars. Methods. High-resolution, multi-fibre spectroscopy and Stromgren photometry are combined to provide as much information on the stars as possible. From this we derive abundances by solving the radiative transfer equations through marcs model atmospheres. Results. We find that the red-giant branch stars of the Hercules dSph galaxy are more metal-poor than estimated in our previous study that was based on photometry alone. From this, we derive a new metallicity calibration for the Stromgren photometry. Additionally, we find an abundance trend such that [Ca/Fe] is higher for more metal-poor stars, and lower for more metal-rich stars, with a spread of about 0.8 dex. The [Ca/Fe] trend suggests an early rapid chemical enrichment through supernovae of type II, followed by a phase of slow star formation dominated by enrichment through supernovae of type Ia. A comparison with isochrones indicates that the red giants in Hercules are older than 10 Gyr.

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

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

  • 4.
    Allende Prieto, C.
    et al.
    Inst Astrofis Canarias, Via Lactea, Tenerife 38205, Spain;Univ La Laguna, Dept Astrofis, E-38206 Tenerife, Spain.
    Koesterke, L.
    Univ Texas Austin, Texas Adv Comp Ctr, Austin, TX 78759 USA.
    Hubeny, I.
    Univ Arizona, Steward Observ, 933 N Cherry Ave, Tucson, AZ 85721 USA.
    Bautista, M. A.
    Western Michigan Univ, Dept Phys, Kalamazoo, MI 49008 USA.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Nahar, S. N.
    Ohio State Univ, Dept Astron, Columbus, OH 43210 USA.
    A collection of model stellar spectra for spectral types B to early-M2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 618, article id A25Article in journal (Refereed)
    Abstract [en]

    Context: Models of stellar spectra are necessary for interpreting light from individual stars, planets, integrated stellar populations, nebulae, and the interstellar medium.

    Aims: We provide a comprehensive and homogeneous collection of synthetic spectra for a wide range of atmospheric parameters and chemical compositions.

    Methods: We compile atomic and molecular data from the literature. We adopt the largest and most recent set of ATLAS9 model atmospheres, and use the radiative code ASS epsilon T.

    Results: The resulting collection of spectra is made publicly available at medium and high-resolution (R lambda/delta lambda = 10 000, 100 000 and 300 000) spectral grids, which include variations in effective temperature between 3500K and 30 000 K, surface gravity (0 <= log g <= 5), and metallicity (-5 <= [Fe/H] <= +0 : 5), spanning the wavelength interval 120-6500 nm. A second set of denser grids with additional dimensions, [alpha/ Fe] and micro-turbulence, are also provided (covering 200-2500 nm). We compare models with observations for a few representative cases.

  • 5.
    Amarsi, A. M.
    et al.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Excitation and charge transfer in low-energy hydrogen atom collisions with neutral carbon and nitrogen2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 625, article id A78Article in journal (Refereed)
    Abstract [en]

    Low-energy inelastic collisions with neutral hydrogen atoms are important processes in stellar atmospheres, and a persistent source of uncertainty in non-LTE modelling of stellar spectra. We have calculated and studied excitation and charge transfer of C I and of N I due to such collisions. We used a previously presented method that is based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions for the adiabatic potential energies, combined with the multichannel Landau-Zener model for the collision dynamics. We find that charge transfer processes typically lead to much larger rate coefficients than excitation processes do, consistent with studies of other atomic species. Two-electron processes were considered and lead to non-zero rate coefficients that can potentially impact statistical equilibrium calculations. However, they were included in the model in an approximate way, via an estimate for the two-electron coupling that was presented earlier in the literature: the validity of these data should be checked in a future work.

  • 6.
    Amarsi, A. M.
    et al.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany;Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, M.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.
    Collet, R.
    Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
    Zatsarinny, O.
    Drake Univ, Dept Phys & Astron, Des Moines, IA 50311 USA.
    Inelastic O plus H collisions and the O I 777 nm solar centre-to-limb variation2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 616, article id A89Article in journal (Refereed)
    Abstract [en]

    The O I 777 nm triplet is a key diagnostic of oxygen abundances in the atmospheres of FGK-type stars; however, it is sensitive to departures from local thermodynamic equilibrium (LTE). The accuracy of non-LTE line formation calculations has hitherto been limited by errors in the inelastic O+H collisional rate coefficients; several recent studies have used the Drawin recipe, albeit with a correction factor S-H that is calibrated to the solar centre-to-limb variation of the triplet. We present a new model oxygen atom that incorporates inelastic O+H collisional rate coefficients using an asymptotic two-electron model based on linear combinations of atomic orbitals, combined with a free electron model based on the impulse approximation. Using a 3D hydrodynamic STAGGER model solar atmosphere and 3D non-LTE line formation calculations, we demonstrate that this physically motivated approach is able to reproduce the solar centre-to-limb variation of the triplet to 0.02 dex, without any calibration of the inelastic collisional rate coefficients or other free parameters. We infer log epsilon(O) = 8.69 +/- 0.03 from the triplet alone, strengthening the case for a low solar oxygen abundance.

  • 7.
    Amarsi, A. M.
    et al.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Collet, R.
    Aarhus Univ, Stellar Astrophys Ctr, Dept Phys & Astron, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
    Grevesse, N.
    Univ Liege, Ctr Spatial Liege, Ave Pre Aily, B-4031 Angleur Liege, Belgium;Univ Liege, Space Sci Technol & Astrophys Res STAR Inst, Allee 6 Aout,17,B5C, B-4000 Liege, Belgium.
    Asplund, M.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.
    3D non-LTE line formation of neutral carbon in the Sun2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 624, article id A111Article in journal (Refereed)
    Abstract [en]

    Carbon abundances in late-type stars are important in a variety of astrophysical contexts. However C I lines, one of the main abundance diagnostics, are sensitive to departures from local thermodynamic equilibrium (LTE). We present a model atom for non-LTE analyses of C I lines, that uses a new, physically-motivated recipe for the rates of neutral hydrogen impact excitation. We analyse C I lines in the solar spectrum, employing a three-dimensional (3D) hydrodynamic model solar atmosphere and 3D non-LTE radiative transfer. We find negative non-LTE abundance corrections for C I lines in the solar photosphere, in accordance with previous studies, reaching up to around 0.1 dex in the disk-integrated flux. We also present the first fully consistent 3D non-LTE solar carbon abundance determination: we infer log is an element of(C) = 8.44 ± 0.02, in good agreement with the current standard value. Our models reproduce the observed solar centre-to-limb variations of various C I lines, without any adjustments to the rates of neutral hydrogen impact excitation, suggesting that the proposed recipe may be a solution to the long-standing problem of how to reliably model inelastic collisions with neutral hydrogen in late-type stellar atmospheres.

  • 8.
    Amarsi, A. M.
    et al.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia..
    Lind, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany..
    Asplund, M.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia..
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Collet, R.
    Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark..
    Non-LTE line formation of Fe in late-type stars - III. 3D non-LTE analysis of metal-poor stars2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 463, no 2, p. 1518-1533Article in journal (Refereed)
    Abstract [en]

    As one of the most important elements in astronomy, iron abundance determinations need to be as accurate as possible. We investigate the accuracy of spectroscopic iron abundance analyses using archetypal metal-poor stars. We perform detailed 3D non-LTE radiative transfer calculations based on 3D hydrodynamic STAGGER model atmospheres, and employ a new model atom that includes new quantum-mechanical neutral hydrogen collisional rate coefficients. With the exception of the red giant HD122563, we find that the 3D non-LTE models achieve Fe I/Fe II excitation and ionization balance as well as not having any trends with equivalent width to within modelling uncertainties of 0.05 dex, all without having to invoke any microturbulent broadening; for HD122563 we predict that the current best parallax-based surface gravity is overestimated by 0.5 dex. Using a 3D non-LTE analysis, we infer iron abundances from the 3D model atmospheres that are roughly 0.1 dex higher than corresponding abundances from 1D MARCS model atmospheres; these differences go in the same direction as the non-LTE effects themselves. We make available grids of departure coefficients, equivalent widths and abundance corrections, calculated on 1D MARCS model atmospheres and horizontally and temporally averaged 3D STAGGER model atmospheres.

  • 9.
    Amarsi, A. M.
    et al.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Nordlander, T.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia;ARC Ctr Excellence All Sky Astrophys 3 Dimens AST, Canberra, ACT, Australia.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Asplund, M.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.
    Collet, R.
    Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
    Lind, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Effective temperature determinations of late-type stars based on 3D non-LTE Balmer line formation2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 615, article id A139Article in journal (Refereed)
    Abstract [en]

    Hydrogen Balmer lines are commonly used as spectroscopic effective temperature diagnostics of late-type stars. However, reliable inferences require accurate model spectra, and the absolute accuracy of classical methods that are based on one-dimensional (1D) hydrostatic model atmospheres and local thermodynamic equilibrium (LTE) is still unclear. To investigate this, we carry out 3D non-LTE calculations for the Balmer lines, performed, for the first time, over an extensive grid of 3D hydrodynamic STAGGER model atmospheres. For H alpha, H beta, and H gamma we find significant 1D non-LTE versus 3D non-LTE differences (3D effects): the outer wings tend to be stronger in 3D models, particularly for H gamma, while the inner wings can be weaker in 3D models, particularly for H alpha. For H alpha, we also find significant 3D LTE versus 3D non-LTE differences (non-LTE effects): in warmer stars (T-eff approximate to 6500 K) the inner wings tend to be weaker in non-LTE models, while at lower effective temperatures (T-eff approximate to 4500 K) the inner wings can be stronger in non-LTE models; the non-LTE effects are more severe at lower metallicities. We test our 3D non-LTE models against observations of well-studied benchmark stars. For the Sun, we infer concordant effective temperatures from H alpha, H beta, and H gamma; however the value is too low by around 50 K which could signal residual modelling shortcomings. For other benchmark stars, our 3D non-LTE models generally reproduce the effective temperatures to within 1 sigma uncertainties. For H alpha, the absolute 3D effects and non-LTE effects can separately reach around 100 K, in terms of inferred effective temperatures. For metal-poor turn-off stars, 1D LTE models of H alpha can underestimate effective temperatures by around 150 K. Our 3D non-LTE model spectra are publicly available, and can be used for more reliable spectroscopic effective temperature determinations.

  • 10.
    Andrae, Rene
    et al.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Fouesneau, Morgan
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Creevey, Orlagh
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Ordenovic, Christophe
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Mary, Nicolas
    Thales Serv, 290 Allee Lac, F-31670 Labege, France.
    Burlacu, Alexandru
    Telespazio France, 26 Ave Jean Francois Champollion, F-31100 Toulouse, France.
    Chaoul, Laurence
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31401 Toulouse, France.
    Jean-Antoine-Piccolo, Anne
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31401 Toulouse, France.
    Kordopatis, Georges
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Lebreton, Yveline
    Univ Rennes 1, Inst Phys Rennes, CNRS, UMR 6251, F-35042 Rennes, France;Univ Paris Diderot, LESIA, Observ Paris, PSL Res Univ,CNRS,UMR 8109,Univ Pierre & Marie Cu, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Panem, Chantal
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31401 Toulouse, France.
    Pichon, Bernard
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Thevenin, Frederic
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Walmsley, Gavin
    Ctr Natl Etud Spatiales, 18 Ave Edouard Belin, F-31401 Toulouse, France.
    Bailer-Jones, Coryn A. L.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    First stellar parameters from Apsis2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 616, article id A8Article in journal (Refereed)
    Abstract [en]

    The second Gaia data release (Gaia DR2) contains, beyond the astrometry, three-band photometry for 1.38 billion sources. One band is the G band, the other two were obtained by integrating the Gaia prism spectra (BP and RP). We have used these three broad photometric bands to infer stellar effective temperatures, T-eff, for all sources brighter than G = 17 mag with T-eff in the range 3000-10 000K (some 161 million sources). Using in addition the parallaxes, we infer the line-of-sight extinction, A(G), and the reddening, E(BP-RP), for 88 million sources. Together with a bolometric correction we derive luminosity and radius for 77 million sources. These quantities as well as their estimated uncertainties are part of Gaia DR2. Here we describe the procedures by which these quantities were obtained, including the underlying assumptions, comparison with literature estimates, and the limitations of our results. Typical accuracies are of order 324K (T-eff), 0.46 mag (A(G)), 0.23 mag (E(BP-RP)), 15% (luminosity), and 10% (radius). Being based on only a small number of observable quantities and limited training data, our results are necessarily subject to some extreme assumptions that can lead to strong systematics in some cases (not included in the aforementioned accuracy estimates). One aspect is the non-negativity contraint of our estimates, in particular extinction, which we discuss. Yet in several regions of parameter space our results show very good performance, for example for red clump stars and solar analogues. Large uncertainties render the extinctions less useful at the individual star level, but they show good performance for ensemble estimates. We identify regimes in which our parameters should and should not be used and we define a "clean" sample. Despite the limitations, this is the largest catalogue of uniformly-inferred stellar parameters to date. More precise and detailed astrophysical parameters based on the full BP/RP spectrophotometry are planned as part of the third Gaia data release.

  • 11.
    Aronson, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Bladh, S.
    Univ Padua, Dipartimento Fis & Astron Galileo Galilei, Vicolo Osservatorio 3, I-35122 Padua, Italy.
    Höfner, Susanne
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Modelling polarized light from dust shells surrounding asymptotic giant branch stars2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 603, article id A116Article in journal (Refereed)
    Abstract [en]

    Context. Winds of asymptotic giant branch (AGB) stars are commonly assumed to be driven by radiative acceleration of dust grains. For M-type AGB stars, the nature of the wind-driving dust species has been a matter of intense debate. A proposed source of the radiation pressure triggering the outflows is photon scattering on Fe-free silicate grains. This wind-driving mechanism requires grain radii of about 0.1-1 micron in order to make the dust particles efficient at scattering radiation around the stellar flux maximum. Grain size is therefore an important parameter for understanding the physics behind the winds of M-type AGB stars. Aims. We seek to investigate the diagnostic potential of scattered polarized light for determining dust grain sizes. Methods. We have developed a new tool for computing synthetic images of scattered light in dust and gas shells around AGB stars, which can be applied to detailed models of dynamical atmospheres and dust-driven winds. Results. We present maps of polarized light using dynamical models computed with the DARWIN code. The synthetic images clearly show that the intensity of the polarized light, the position of the inner edge of the dust shell, and the size of the dust grains near the inner edge are all changing with the luminosity phase. Non-spherical structures in the dust shells can also have an impact on the polarized light. We simulate this effect by combining different pulsation phases into a single 3D structure before computing synthetic images. An asymmetry of the circumstellar envelope can create a net polarization, which can be used as diagnostics for the grain size. The ratio between the size of the scattering particles and the observed wavelength determines at what wavelengths net polarization switches direction. If observed, this can be used to constrain average particle sizes.

  • 12. Arroyo-Torres, B.
    et al.
    Wittkowski, M.
    Chiavassa, A.
    Scholz, M.
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Marcaide, J. M.
    Hauschildt, P. H.
    Wood, P. R.
    Abellan, F. J.
    What causes the large extensions of red supergiant atmospheres?: Comparisons of interferometric observations with 1D hydrostatic, 3D convection, and 1D pulsating model atmospheres2015In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 575, article id A50Article in journal (Refereed)
    Abstract [en]

    Aims. This research has two main goals. First, we present the atmospheric structure and the fundamental parameters of three red supergiants (RSGs), increasing the sample of RSGs observed by near-infrared spectro-interferometry. Additionally, we test possible mechanisms that may explain the large observed atmospheric extensions of RSGs. Methods. We carried out spectro-interferometric observations of the.RSGs V602 Car, EID 95687, and EID 183589 in the near-infrared K-band (1.92-2.47 mu m) with the VLTI/AMBER instrument at medium spectral resolution (R similar to 1500). To categorize and comprehend the extended atmospheres, we compared our observational results to predictions by available hydrostatic PHOENIX, available 3D convection, and new 1D self-excited pulsation models of RSGs. Results. Our near-infrared flux spectra of V602 Car, HD 95687, and HD 183589 are well reproduced by the PHOENIX model atmospheres. The continuum visibility values are consistent with a limb-darkened disk as predicted by the PHOENIX models, allowing us to determine the angular diameter and the fundamental parameters of our sources. Nonetheless, in the case of V602 Car and HD 95686, the PHOENIX model visibilities do not predict the large observed extensions of molecular layers, most remarkably in the CO bands. Likewise, the 3D convection models and the ID pulsation models with typical parameters of RSGs lead to compact atmospheric structures as well, which are similar to the structure of the hydrostatic PHOENIX models. They can also not explain the observed decreases in the visibilities and thus the large atmospheric molecular extensions. The full sample of our RSGs indicates increasing observed atmospheric extensions with increasing luminosity and decreasing surface gravity, and no correlation with effective temperature or variability amplitude. Conclusions. The location of our RSG sources in the Hertzsprung-Russell diagram is contirm.ed to be consistent with the red limits of recent evolutionary tracks. The observed extensions of the atmospheric layers of our sample of RSGs are comparable to those of Mira stars. This phenomenon is not predicted by any of the considered model atmospheres including as 311) convection and new 1D pulsation models of.RSGs. This confirms that neither convection nor pulsation alone can levitate the molecular atmospheres of.RSGs. Our observed correlation of atmospheric extension with luminosity supports a scenario of radiative acceleration on Doppler-shifted molecular lines.

  • 13.
    Arroyo-Torres, B.
    et al.
    Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain..
    Wittkowski, M.
    ESO, Garching, Germany..
    Marcaide, J. M.
    Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain.;Donostia Int Phys Ctr, Donostia San Sebastian, Spain..
    Abellan, F. J.
    Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain..
    Chiavassa, A.
    Univ Nice Sophia Antipolis, Lab Lagrange, CNRS, Observ Cote Azur, Sophia Anitpolis, France..
    Fabregat, J.
    Univ Valencia, Astron Observ, E-46003 Valencia, Spain..
    Freytag, Bernd
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Guirado, J. C.
    Univ Valencia, Dept Astron & Astrofis, E-46100 Burjassot, Spain.;Univ Valencia, Astron Observ, E-46003 Valencia, Spain..
    Hauschildt, P. H.
    Hamburger Sternwarte, Hamburg, Germany..
    Marti-Vidal, I.
    Chalmers, Onsala Space Observ, Gothenburg, Sweden..
    Quirrenbach, A.
    Heidelberg Univ, Zentrum Astron, Landessternwarte, D-69115 Heidelberg, Germany..
    Scholz, M.
    Heidelberg Univ, Zentrum Astron, Inst Theoret Astrophys, D-69115 Heidelberg, Germany.;Univ Sydney, Sch Phys, Sydney Inst Astron, Sydney, NSW 2006, Australia..
    Wood, P. R.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT, Australia..
    VLTI/AMBER Studies of the Atmospheric Structure and Fundamental Parameters of Red Giant and Supergiant Stars2015In: WHY GALAXIES CARE ABOUT AGB STARS III: A CLOSER LOOK IN SPACE AND TIME, ASTRONOMICAL SOC PACIFIC , 2015, Vol. 497, p. 91-96Conference paper (Other academic)
    Abstract [en]

    We present recent near-IR interferometric studies of red giant and super giant stars, which are aimed at obtaining information on the structure of the atmospheric layers and constraining the fundamental parameters of these objects. The observed visibilities of six red supergiants (RSGs), and also of one of the five red giants observed, indicate large extensions of the molecular layers, as previously observed for Mira stars. These extensions are not predicted by hydrostatic PHOENIX model atmospheres, hydrodynamical (RED) simulations of stellar convection, or self-excited pulsation models. All these models based on parameters of RSGs lead to atmospheric structures that are too compact compared to our observations. We discuss how alternative processes might explain the atmospheric extensions for these objects. As the continuum appears to be largely free of contamination by molecular layers, we can estimate reliable Rosseland angular radii for our stars. Together with distances and bolometric fluxes, we estimate the effective temperatures and luminosities of our targets, locate them in the HR diagram, and compare their positions to recent evolutionary tracks.

  • 14.
    Attree, N.
    et al.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Groussin, O.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Jorda, L.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Nebouy, D.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Thomas, N.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Brouet, Y.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Kuehrt, E.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Preusker, F.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Scholten, F.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Knollenberg, J.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Hartogh, P.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Sierks, H.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Barbieri, C.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Lamy, P.
    Aix Marseille Univ, CNRS, LAM, Marseille, France..
    Rodrigo, R.
    INTA CSIC, Ctr Astrobiol, Madrid 28691, Spain.;Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Koschny, D.
    ESA, Sci Support Off, NL-2201 Noordwijk, Netherlands..
    Rickman, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. PAS Space Res Ctr, Bartycka 18A, PL-00716 Warsaw, Poland..
    Keller, H. U.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany.;TU Braunschweig, Inst Geophys & Extraterrestrial Phys, D-38106 Braunschweig, Germany..
    A'Hearn, M. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Auger, A. -T
    Barucci, M. A.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Bertaux, J. -L
    Bertini, I.
    Bodewits, D.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Boudreault, S.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Cremonese, G.
    Da Deppo, V.
    CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Davidsson, B.
    Int Space Sci Inst, Hallerstr 6, CH-3012 Bern, Switzerland..
    Debei, S.
    Univ Padua, Dept Ind Engn, I-35131 Padua, Italy..
    De Cecco, M.
    Univ Trento, UNITN, Via Mesiano 77, I-38100 Trento, Italy..
    Deller, J.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    El-Maarry, M. R.
    Univ Bern, Physikal Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Fornasier, S.
    Univ Paris Diderot, Univ Paris 06, CNRS, LESIA,Obs Paris, 5 Pl J Janssen, F-92195 Meudon, France..
    Fulle, M.
    INAF Osservatorio Astronom, Via Tiepolo 11, I-34143 Trieste, Italy..
    Gutierrez, P. J.
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Guettler, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Hviid, S.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Ip, W. -H
    Kovacs, G.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kramm, J. R.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Kueppers, M.
    ESA, European Space Astron Ctr, Operat Dept, POB 78, Madrid 28691, Spain..
    Lara, L. M.
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Lazzarin, M.
    Moreno, J. J. Lopez
    CSIC, Inst Astrofis Andalucia, Glorieta Astronomia S-N, Granada 18008, Spain..
    Lowry, S.
    Univ Kent, Sch Phys Sci SEPnet, Ctr Astrophys & Planetary Sci, Canterbury CT2 7NH, Kent, England..
    Marchi, S.
    Southwest Res Inst, 1050 Walnut St, Boulder, CO 80302 USA..
    Marzari, F.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy..
    Mottola, S.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Naletto, G.
    Padova Univ, Dept Phys & Astron, Vicolo Osservatorio 3, I-35122 Padua, Italy.;Univ Padua, Ctr Ateneo Studi Attivita Spaziali Giuseppe Colom, Via Venezia 15, I-35131 Padua, Italy.;CNR, IFN UOS Padova LUXOR, Via Trasea 7, I-35131 Padua, Italy..
    Oklay, N.
    Inst Planetary Res DLR, Rutherfordstr 2, Berlin, Germany..
    Pajola, M.
    NASA, Ames Res Ctr, Moffett Field, CA 94035 USA..
    Toth, I.
    MTA CSFK Konkoly Observ, Konkoly Thege M Ut 15-17, H-1121 Budapest, Hungary..
    Tubiana, C.
    Max Planck Inst Sonnensyst Forsch, D-37077 Gottingen, Germany..
    Vincent, J. -B
    Shi, X.
    Tensile strength of 67P/Churyumov-Gerasimenko nucleus material from overhangs2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 611, article id A33Article in journal (Refereed)
    Abstract [en]

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

  • 15. 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.

  • 16.
    Babusiaux, C.
    et al.
    Univ Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble, France;Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    van Leeuwen, F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Barstow, M. A.
    Univ Leicester, Dept Phys & Astron, Leicester Inst Space & Earth Observat, Univ Rd, Leicester LE1 7RH, Leics, England.
    Jordi, C.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Vallenari, A.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Bossini, D.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Bressan, A.
    SISSA, Via Bonomea 265, I-34136 Trieste, Italy.
    Cantat-Gaudin, T.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy;Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    van Leeuwen, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Brown, A. G. A.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.
    Prusti, T.
    ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
    de Bruijne, J. H. J.
    ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
    Bailer-Jones, C. A. L.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Biermann, M.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Evans, D. W.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Eyer, L.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Jansen, F.
    ESA ESTEC, Directorate Sci, Operat Dept, Miss Operat Div, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
    Klioner, S. A.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Lammers, U.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Lindegren, L.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.
    Luri, X.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Mignard, F.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Panem, C.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Pourbaix, D.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium;FRS FNRS, Rue Egmont 5, B-1000 Brussels, Belgium.
    Randich, S.
    INAF Osservatorio Astrofis Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy.
    Sartoretti, P.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Siddiqui, H. I.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Soubiran, C.
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.
    Walton, N. A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Arenou, F.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Bastian, U.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Cropper, M.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Drimmel, R.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Katz, D.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Lattanzi, M. G.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Bakker, J.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Cacciari, C.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Castaneda, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Chaoul, L.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Cheek, N.
    ESA ESAC, Serco Gest Negocios, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    De Angeli, F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Fabricius, C.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Guerra, R.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Holl, B.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Masana, E.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Messineo, R.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Mowlavi, N.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Nienartowicz, K.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Panuzzo, P.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Portell, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Riello, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Seabroke, G. M.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Tanga, P.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Thevenin, F.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Gracia-Abril, G.
    ESAC, Gaia DPAC Project Off, Camino Bajo Castillo S-N, Madrid 28692, Spain;Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Comoretto, G.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Garcia-Reinaldos, M.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Teyssier, D.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Altmann, M.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany;Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Andrae, R.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Audard, M.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Bellas-Velidis, I.
    Natl Observ Athens I Metaxa & Vas Pavlou Palaia P, Athens 15236, Greece.
    Benson, K.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Berthier, J.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France.
    Blomme, R.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Burgess, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Busso, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Carry, B.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France;Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Cellino, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Clementini, G.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Clotet, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Creevey, O.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Davidson, M.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    De Ridder, J.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
    Delchambre, L.
    Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Dell'Oro, A.
    INAF Osservatorio Astrofis Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy.
    Ducourant, C.
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.
    Fernandez-Hernandez, J.
    ESA ESAC, ATG Europe, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Fouesneau, M.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Fremat, Y.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Galluccio, L.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Garcia-Torres, M.
    Univ Pablo Olavide, Area Lenguajes Sistemas Informat, Ctr Utrera,Km 1, Seville 41013, Spain.
    Gonzalez-Nunez, J.
    ESA ESAC, Serco Gest Negocios, Camino Bajo Castillo S-N, Madrid 28692, Spain;Univ Vigo, ETSE Telecomun, Campus Lagoas Marcosende, Vigo 36310, Spain.
    Gonzalez-Vidal, J. J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Gosset, E.
    FRS FNRS, Rue Egmont 5, B-1000 Brussels, Belgium;Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Guy, L. P.
    Large Synopt Survey Telescope, 950 N Cherry Ave, Tucson, AZ 85719 USA;Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Halbwachs, J. -L
    Hambly, N. C.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    Harrison, D. L.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England;Univ Cambridge, Kavli Inst Cosmol, Madingley Rd, Cambride CB3 0HA, England.
    Hernandez, J.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Hestroffer, D.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France.
    Hodgkin, S. T.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Hutton, A.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Jasniewicz, G.
    Univ Montpellier, Lab Univ & Particules Montpellier, Pl Eugene Bataillon,CC72, F-34095 Montpellier 05, France.
    Jean-Antoine-Piccolo, A.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Jordan, S.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Korn, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Krone-Martins, A.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Lanzafame, A. C.
    Univ Catania, Dipartimento Fis & Astron, Sez Astrofis, Via S Sofia 78, I-95123 Catania, Italy;INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Lebzelter, T.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
    Loeffler, W.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Manteiga, M.
    Univ A Coruna, CITIC Astron & Astrophys, Campus Elvina S-N, La Coruna 15071, Spain;Univ A Coruna, CITIC, Dept Comp Sci, Campus Elvina S-N, La Coruna 15071, Spain.
    Marrese, P. M.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy;ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.
    Martin-Fleitas, J. M.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Moitinho, A.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Mora, A.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Muinonen, K.
    Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland;Finnish Geospatial Res Inst FGI, Geodeetinrinne 2, Masala 02430, Finland.
    Osinde, J.
    ESA ESAC, Isdefe, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Pancino, E.
    ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy;INAF Osservatorio Astrofis Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy.
    Pauwels, T.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Petit, J. -M
    Recio-Blanco, A.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Richards, P. J.
    Rutherford Appleton Lab, STFC, Harwell OX11 0QX, Didcot, England.
    Rimoldini, L.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Robin, A. C.
    Univ Bourgogne Franche Comte, Inst UTINAM UMR6213, CNRS, OSU THETA Franche Comte Bourgogne, F-25000 Besancon, France.
    Sarro, L. M.
    UNED, Dept Inteligencia Artificial, C Juan Rosal 16, Madrid 28040, Spain.
    Siopis, C.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium.
    Smith, M.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Sozzetti, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Sueveges, M.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Torra, J.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    van Reeven, W.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Abbas, U.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Abreu Aramburu, A.
    ESA ESAC, Elecnor Deimos Space, Camino Bajo Castillo S-N, Madrid 28692, Spain;Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany;INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy;Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain;Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland;Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Accart, S.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Aerts, C.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
    Altavilla, G.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy;ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy;INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Alvarez, M. A.
    Univ A Coruna, CITIC, Dept Comp Sci, Campus Elvina S-N, La Coruna 15071, Spain.
    Alvarez, R.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Alves, J.
    Univ Vienna, Dept Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
    Anderson, R. I.
    European Southern Observ, Karl Schwarzschild Str 2, D-85748 Garching, Germany;Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Andrei, A. H.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France;ON MCTI BR, Rua Gal Jose Cristino 77, BR-20921400 Rio De Janeiro, Brazil;OV UFRJ BR, Ladeira Pedro Antonio 43, BR-20080090 Rio De Janeiro, Brazil.
    Anglada Varela, E.
    ESA ESAC, ATG Europe, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Antiche, E.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Antoja, T.
    ESA ESTEC, Directorate Sci, Sci Support Off, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands;Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Arcay, B.
    Univ A Coruna, CITIC, Dept Comp Sci, Campus Elvina S-N, La Coruna 15071, Spain.
    Astraatmadja, T. L.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany;Carnegie Inst Sci, Dept Terr Magnetism, 5241 Broad Branch Rd,NW, Washington, DC 20015 USA.
    Bach, N.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Baker, S. G.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Balaguer-Nunez, L.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Balm, P.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Barache, C.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Barata, C.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Barbato, D.
    Univ Torino, Dipartimento Fis, Via Pietro Giuria 1, I-10125 Turin, Italy;INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Barblan, F.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Barrado, D.
    ESA ESAC, Dept Astrofis, Ctr Astrobiol, CSIC INTA, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Barros, M.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Bartholome Munoz, S.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Bassilana, J. -L
    Becciani, U.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Bellazzini, M.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Berihuete, A.
    Univ Cadiz, Dept Estadist, Calle Republica Arabe Saharawi S-N, Puerto Real 11510, Spain;Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany;Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Bertones, S.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France;INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy;Bern Univ, Astron Inst, Sidlerstr 5, CH-3012 Bern, Switzerland.
    Bianchi, L.
    EURIX Srl, Corso Vittorio Emanuele 2 61, I-10128 Turin, Italy.
    Bienayme, O.
    Univ Strasbourg, CNRS, Observ Astron Strasbourg, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France.
    Blanco-Cuaresma, S.
    Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA;Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France;Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Boch, T.
    Univ Strasbourg, CNRS, Observ Astron Strasbourg, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France.
    Boeche, C.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Bombrun, A.
    ESA ESAC, HE Space Operat BV, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Borrachero, R.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Bouquillon, S.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Bourda, G.
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.
    Bragaglia, A.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Bramante, L.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Breddels, M. A.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands.
    Brouillet, N.
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.
    Bruesemeister, T.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Brugaletta, E.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Bucciarelli, B.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Burlacu, A.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Busonero, D.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Butkevich, A. G.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Buzzi, R.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Caffau, E.
    Cancelliere, R.
    Univ Turin, Dept Comp Sci, Corso Svizzera 185, I-10149 Turin, Italy.
    Cannizzaro, G.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;SRON, Netherlands Inst Space Res, Sorbonnelaan 2, NL-3584CA Utrecht, Netherlands.
    Carballo, R.
    Univ Cantabria, Dept Matemat Aplicada & Ciencias Comp, ETS Ingenieros Caminos Canales & Puertos, Avda Castros S-N, E-39005 Santander, Spain.
    Carlucci, T.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Carrasco, J. M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Casamiquela, L.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Castellani, M.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy.
    Castro-Ginard, A.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Charlot, P.
    Univ Bordeaux, CNRS, Lab Astrophys Bordeaux, B18N,Allee Geoffroy St Hilaire, F-33615 Pessac, France.
    Chemin, L.
    Univ Antofagasta, Unidad Astron, Ave Angamos 601, Antofagasta 1270300, Chile.
    Chiavassa, A.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Cocozza, G.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Costigan, G.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.
    Cowell, S.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Crifo, F.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Crosta, M.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Crowley, C.
    ESA ESAC, HE Space Operat BV, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Cuypers, J.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Dafonte, C.
    Univ A Coruna, CITIC, Dept Comp Sci, Campus Elvina S-N, La Coruna 15071, Spain.
    Damerdji, Y.
    CRAAG, Route Observ Bp 63, Algiers 16340, Algeria;Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Dapergolas, A.
    Natl Observ Athens I Metaxa & Vas Pavlou Palaia P, Athens 15236, Greece.
    David, P.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France.
    David, M.
    Univ Antwerp, Onderzoeksgroep Toegepaste Wiskunde, Middelheimlaan 1, B-2020 Antwerp, Belgium.
    de laverny, P.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    De Luise, F.
    INAF, Osservatorio Astron Abruzzo, Via Mentore Maggini, I-64100 Teramo, Italy.
    De March, R.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    de Martino, D.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    de Souza, R.
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, BR-05508900 Sao Paulo, Brazil.
    de Torres, A.
    ESA ESAC, HE Space Operat BV, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Debosscher, J.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
    del Pozo, E.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Delbo, M.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Delgado, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Delgado, H. E.
    UNED, Dept Inteligencia Artificial, C Juan Rosal 16, Madrid 28040, Spain.
    Diakite, S.
    Univ Bourgogne Franche Comte, Inst UTINAM UMR6213, CNRS, OSU THETA Franche Comte Bourgogne, F-25000 Besancon, France.
    Diener, C.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Distefano, E.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Dolding, C.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Drazinos, P.
    Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece.
    Duran, J.
    ESA ESAC, Isdefe, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Edvardsson, Bengt
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Enke, H.
    AIP, Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Eriksson, Kjell
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Esquej, P.
    ESA ESAC, RHEA, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Bontemps, G. Eynard
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Fabre, C.
    CNES Ctr Spatial Toulouse, ATOS, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Fabrizio, M.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy;ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.
    Faigler, S.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel.
    Falcao, A. J.
    UNINOVA CTS, Campus FCT UNL, P-2829516 Caparica, Portugal.
    Casas, M. Farras
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Federici, L.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Fedorets, G.
    Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland.
    Fernique, P.
    Univ Strasbourg, CNRS, Observ Astron Strasbourg, UMR 7550, 11 Rue Univ, F-67000 Strasbourg, France.
    Figueras, F.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Filippi, F.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Findeisen, K.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Fonti, A.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Fraile, E.
    ESA ESAC, RHEA, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Fraser, M.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England;Univ Coll Dublin, Sch Phys, OBrien Ctr Sci North, Dublin 4, Ireland.
    Frezouls, B.
    Univ Antwerp, Onderzoeksgroep Toegepaste Wiskunde, Middelheimlaan 1, B-2020 Antwerp, Belgium.
    Gai, M.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Galleti, S.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Garabato, D.
    Univ A Coruna, CITIC, Dept Comp Sci, Campus Elvina S-N, La Coruna 15071, Spain.
    Garcia-Sedano, F.
    UNED, Dept Inteligencia Artificial, C Juan Rosal 16, Madrid 28040, Spain.
    Garofalo, A.
    Univ Bologna, Dipartimento Fis & Astron, Via Piero Gobetti 93-2, I-40129 Bologna, Italy;INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Garralda, N.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Gavel, Alvin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Gavras, P.
    Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece;Natl Observ Athens I Metaxa & Vas Pavlou Palaia P, Athens 15236, Greece;Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Gerssen, J.
    AIP, Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Geyer, R.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Giacobbe, P.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Gilmore, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Girona, S.
    Ctr Nacl Super Comp, Barcelona Supercomputing Ctr, C Jordi Girona 29,Ed Nexus 2, Barcelona 08034, Spain.
    Giuffrida, G.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy;ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.
    Glass, F.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Gomes, M.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Granvik, M.
    Lulea Univ Technol, Dept Comp Sci Elect & Space Engn, Box 848, S-98128 Kiruna, Sweden;Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland.
    Gueguen, A.
    Max Planck Inst Extraterrestrial Phys, High Energy Grp, Giessenbachstr, D-85741 Garching, Germany;Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Guerrier, A.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Guiraud, J.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Gutierrez-Sanchez, R.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Haigron, R.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Hatzidimitriou, D.
    Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece;Natl Observ Athens I Metaxa & Vas Pavlou Palaia P, Athens 15236, Greece.
    Hauser, M.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany;Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Haywood, M.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Heiter, Ulrike
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy.
    Helmi, A.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands.
    Heu, J.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Hilger, T.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Hobbs, D.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.
    Hofmann, W.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Holland, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Huckle, H. E.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England.
    Hypki, A.
    Adam Mickiewicz Univ, Astron Observ Inst, Fac Phys, Sloneczna 36, PL-60286 Poznan, Poland;Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.
    Icardi, V.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Janssen, K.
    AIP, Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Jevardat de Fombelle, G.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Jonker, P. G.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;SRON, Netherlands Inst Space Res, Sorbonnelaan 2, NL-3584CA Utrecht, Netherlands.
    Juhasz, A. L.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary;Eotvos Lorand Univ, Egyet Ter 1-3, H-1053 Budapest, Hungary.
    Julbe, F.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Karampelas, A.
    Amer Community Sch Athens, 129 Aghias Paraskevis Ave & Kazantzaki St, Athens 15234, Greece;Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece.
    Kewley, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Klar, J.
    AIP, Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Kochoska, A.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia;Villanova Univ, Dept Astrophys & Planetary Sci, 800 Lancaster Ave, Villanova, PA 19085 USA.
    Kohley, R.
    ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Kolenberg, K.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium;Univ Antwerp, Phys Dept, Groenenborgerlaan 171, B-2020 Antwerp, Belgium;Harvard Smithsonian Ctr Astrophys, 60 Garden St, Cambridge, MA 02138 USA.
    Kontizas, M.
    Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece.
    Kontizas, E.
    Natl Observ Athens I Metaxa & Vas Pavlou Palaia P, Athens 15236, Greece.
    Koposov, S. E.
    Carnegie Mellon Univ, McWilliams Ctr Cosmol, Dept Phys, 5000 Forbes Ave, Pittsburgh, PA 15213 USA;Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Kordopatis, G.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Kostrzewa-Rutkowska, Z.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;SRON, Netherlands Inst Space Res, Sorbonnelaan 2, NL-3584CA Utrecht, Netherlands.
    Koubsky, P.
    Acad Sci Czech Republ, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic.
    Lambert, S.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Lanza, A. F.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Lasne, Y.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Lavigne, J. -B
    Le Fustec, Y.
    CNES Ctr Spatial Toulouse, Telespazio, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Le Poncin-Lafitte, C.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Lebreton, Y.
    Univ Rennes 1, Inst Phys Rennes, F-35042 Rennes, France;Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Leccia, S.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    Leclerc, N.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Lecoeur-Taibi, I.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Lenhardt, H.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Leroux, F.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Liao, S.
    Chinese Acad Sci, Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030, Peoples R China;INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy;Univ Chinese Acad Sci, Sch Astron & Space Sci, Beijing 100049, Peoples R China.
    Licata, E.
    EURIX Srl, Corso Vittorio Emanuele 2 61, I-10128 Turin, Italy.
    Lindstrom, H. E. P.
    Univ Copenhagen, Niels Bohr Inst, Juliane Maries Vej 30, DK-2100 Copenhagen, Denmark;DXC Technol, Retortvej 8, DK-2500 Valby, Denmark.
    Lister, T. A.
    Las Cumbres Observ, 6740 Cortona Dr Suite, Goleta, CA 93117 USA.
    Livanou, E.
    Univ Athens, Dept Astrophys Astron & Mech, Panepistimiopolis, Athens 15783, Greece.
    Lobel, A.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Lopez, M.
    ESA ESAC, Dept Astrofis, Ctr Astrobiol, CSIC INTA, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Managau, S.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Mann, R. G.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    Mantelet, G.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Marchal, O.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Marchant, J. M.
    Liverpool John Moores Univ, Astrophys Res Inst, 146 Brownlow Hill, Liverpool L3 5RF, Merseyside, England.
    Marconi, M.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    Marinoni, S.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy;ASI, Space Sci Data Ctr, Via Politecn SNC, I-00133 Rome, Italy.
    Marschalko, G.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary;Univ Szeged, Baja Observ, Szegedi Ut II 70, H-6500 Baja, Hungary.
    Marshall, D. J.
    Univ Paris Diderot, Lab AIM, IRFU Serv Astrophys, CEA DSM CNRS, Bat 709,CEA Saclay, F-91191 Gif Sur Yvette, France.
    Martino, M.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Marton, G.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.
    Mary, N.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Massari, D.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands.
    Matijevic, G.
    AIP, Leibniz Inst Astrophys Potsdam, Sternwarte 16, D-14482 Potsdam, Germany.
    Mazeh, T.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel.
    McMillan, P. J.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.
    Messina, S.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Michalik, D.
    Lund Univ, Dept Astron & Theoret Phys, Lund Observ, Box 43, S-22100 Lund, Sweden.
    Millar, N. R.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Molina, D.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Molinaro, R.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    Molnar, L.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.
    Montegriffo, P.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Mor, R.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Morbidelli, R.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Morel, T.
    Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Morris, D.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    Mulone, A. F.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Muraveva, T.
    Musella, I.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    Nelemans, G.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
    Nicastro, L.
    INAF, Osservatorio Astrofis & Sci Spazio Bologna, Via Piero Gobetti 93-3, I-40129 Bologna, Italy.
    Noval, L.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    O'Mullane, W.
    Large Synopt Survey Telescope, 950 N Cherry Ave, Tucson, AZ 85719 USA;ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Ordenovic, C.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Ordonez-Blanco, D.
    Univ Geneva, Dept Astron, Chemin Ecogia 16, CH-1290 Versoix, Switzerland.
    Osborne, P.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Pagani, C.
    Univ Leicester, Dept Phys & Astron, Leicester Inst Space & Earth Observat, Univ Rd, Leicester LE1 7RH, Leics, England.
    Pagano, I.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Pailler, F.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Palacin, H.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Palaversa, L.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England;Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Panahi, A.
    Tel Aviv Univ, Sch Phys & Astron, IL-6997801 Tel Aviv, Israel.
    Pawlak, M.
    Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw, Poland;Charles Univ Prague, Inst Theoret Phys, Fac Math & Phys, Prague, Czech Republic.
    Piersimoni, A. M.
    INAF, Osservatorio Astron Abruzzo, Via Mentore Maggini, I-64100 Teramo, Italy.
    Pineau, F. -X
    Plachy, E.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.
    Plum, G.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Poggio, E.
    Univ Torino, Dipartimento Fis, Via Pietro Giuria 1, I-10125 Turin, Italy;INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Poujoulet, E.
    CNES Ctr Spatial Toulouse, AKKA, 18 Ave Edouard Belin, F-31401 Toulouse 9, France;ESA ESTEC, HE Space Operat BV, Keplerlaan 1, NL-2201 AZ Noordwijk, Netherlands.
    Prsa, A.
    Villanova Univ, Dept Astrophys & Planetary Sci, 800 Lancaster Ave, Villanova, PA 19085 USA.
    Pulone, L.
    INAF, Osservatorio Astron Roma, Via Frascati 33, I-00078 Monte Porzio Catone, Italy.
    Racero, E.
    ESA ESAC, Serco Gest Negocios, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Ragaini, S.
    Rambaux, N.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France.
    Ramos-Lerate, M.
    ESA ESAC, Vitrociset Belgium, Camino Bajo Castillo S-N, Madrid 28692, Spain;Space Telescope Sci Inst, 3700 San Martin Dr, Baltimore, MD 21218 USA.
    Regibo, S.
    Katholieke Univ Leuven, Inst Sterrenkunde, Celestijnenlaan 200D, B-3001 Leuven, Belgium.
    Reyle, C.
    Univ Bourgogne Franche Comte, Inst UTINAM UMR6213, CNRS, OSU THETA Franche Comte Bourgogne, F-25000 Besancon, France.
    Riclet, F.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Ripepi, V.
    INAF, Osservatorio Astron Capodimonte, Via Moiariello 16, I-80131 Naples, Italy.
    Riva, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Rivard, A.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Rixon, G.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Roegiers, T.
    ESA ESAC, QUASAR Sci Resources, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Roelens, M.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Romero-Gomez, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Rowell, N.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    Royer, F.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Ruiz-Dern, L.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Sadowski, G.
    Univ Libre Bruxelles, Inst Astron & Astrophys, CP 226,Blvd Triomphe, B-1050 Brussels, Belgium.
    Sagrista Selles, T.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Sahlmann, J.
    Fork Res, Rua Cruzado Osberno,Lt 1,9 Esq, Lisbon, Portugal;ESA ESAC, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Salgado, J.
    CNES Ctr Spatial Toulouse, APAVE SUDEUROPE SAS, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Salguero, E.
    ESA ESAC, ATG Europe, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Sanna, N.
    INAF Osservatorio Astrofis Arcetri, Largo Enrico Fermi 5, I-50125 Florence, Italy.
    Santana-Ros, T.
    Adam Mickiewicz Univ, Astron Observ Inst, Fac Phys, Sloneczna 36, PL-60286 Poznan, Poland.
    Sarasso, M.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Savietto, H.
    Nord Optic Telescope, Rambla Jose Ana Fernandez Perez 7, Brena Baja 38711, Spain.
    Schultheis, M.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Sciacca, E.
    INAF, Osservatorio Astrofis Catania, Via S Sofia 78, I-95123 Catania, Italy.
    Segol, M.
    Spanish Virtual Observ, Santander, Spain.
    Segovia, J. C.
    ESA ESAC, Serco Gest Negocios, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Segransan, D.
    Univ Geneva, Dept Astron, Chemin Maillettes 51, CH-1290 Versoix, Switzerland.
    Shih, I-C
    Siltala, L.
    INAF, Fdn Galileo Galilei, Rambla Jose Ana Fernandez Perez 7, Brena Baja 38712, Santa Cruz Tene, Spain;Univ Helsinki, Dept Phys, FIN-00014 Helsinki, Finland.
    Silva, A. F.
    Univ Lisbon, CENTRA, FCUL, Campo Grande,Edif C8, P-1749016 Lisbon, Portugal.
    Smart, R. L.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Smith, K. W.
    Max Planck Inst Astron, Konigstuhl 17, D-69117 Heidelberg, Germany.
    Solano, E.
    ESA ESAC, Dept Astrofis, Ctr Astrobiol, CSIC INTA, Camino Bajo Castillo S-N, Madrid 28692, Spain;ESA ESAC, INSA, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Solitro, F.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Sordo, R.
    INAF Osservatorio Astron Padova, Vicolo Osservatorio 5, I-35122 Padua, Italy.
    Soria Nieto, S.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Souchay, J.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Spagna, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Spoto, F.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France;Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Stampa, U.
    Heidelberg Univ, Zentrum Astron, Astron Rechen Inst, Monchhofstr 12-14, D-69120 Heidelberg, Germany.
    Steele, I. A.
    Liverpool John Moores Univ, Astrophys Res Inst, 146 Brownlow Hill, Liverpool L3 5RF, Merseyside, England.
    Steidelmueller, H.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Stephenson, C. A.
    ESA ESAC, Telespazio Vega UK Ltd, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Stoev, H.
    Univ Complutense Madrid, Dept Arquitectura Computadores & Automat, Fac Informat, C Prof Jose Garcia Santesmases S-N, E-28040 Madrid, Spain.
    Suess, F. F.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Surdej, J.
    Univ Liege, Inst Astrophys & Geophys, 19c Allee 6 Aout, B-4000 Liege, Belgium.
    Szabados, L.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.
    Szegedi-Elek, E.
    Hungarian Acad Sci, Konkoly Observ, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary.
    Tapiador, D.
    Univ Bristol, HH Wills Phys Lab, Tyndall Ave, Bristol BS8, Avon, England;IEEC, Gran Capita 2-4,08034, Bristol BS8 1TL, Avon, England.
    Taris, F.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Tauran, G.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Taylor, M. B.
    Univ Vigo, Appl Phys Dept, Vigo 36310, Spain.
    Teixeira, R.
    Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Rua Matao 1226,Cidade Univ, BR-05508900 Sao Paulo, Brazil.
    Terrett, D.
    Rutherford Appleton Lab, STFC, Harwell OX11 0QX, Didcot, England.
    Teyssandier, P.
    Sorbonne Univ, LNE, Univ PSL, Observ Paris,SYRTE,CNRS, 61 Ave Observ, F-75014 Paris, France.
    Thuillot, W.
    Univ Lille, Sorbonne Univ, Univ PSL, Observ Paris,IMCCE, 77 Av Denfert Rochereau, F-75014 Paris, France.
    Titarenko, A.
    Univ Cote Azur, Observ Cote Azur, CNRS, Lab Lagrange, Bd Observ,CS 34229, F-06304 Nice 4, France.
    Clotet, F. Torra
    Aarhus Univ, Stellar Astrophys Ctr, Dept Phys & Astron, 120 Ny Munkegade,Bldg 1520, DK-8000 Aarhus, Denmark.
    Turon, C.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Ulla, A.
    Univ Bonn, Argelander Inst Astron, Hugel 71, D-53121 Bonn, Germany.
    Utrilla, E.
    ESA ESAC, Aurora Technol, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    Uzzi, S.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Vaillant, M.
    CNES Ctr Spatial Toulouse, Thales Serv, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Valentini, G.
    INAF, Osservatorio Astron Abruzzo, Via Mentore Maggini, I-64100 Teramo, Italy.
    Valette, V.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    van Elteren, A.
    Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden, Netherlands.
    Van Hemelryck, E.
    Royal Observ Belgium, Ringlaan 3, B-1180 Brussels, Belgium.
    Vaschetto, M.
    ALTEC SpA, Corso Marche 79, I-10146 Turin, Italy.
    Vecchiato, A.
    INAF Osservatorio Astrofis Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Veljanoski, J.
    Univ Groningen, Kapteyn Astron Inst, Landleven 12, NL-9747 AD Groningen, Netherlands.
    Viala, Y.
    Univ PSL, GEPI, Observ Paris, CNRS, 5 Pl Jules Janssen, F-92190 Meudon, France.
    Vicente, D.
    Ctr Nacl Super Comp, Barcelona Supercomputing Ctr, C Jordi Girona 29,Ed Nexus 2, Barcelona 08034, Spain.
    Vogt, S.
    ESA ESAC, QUASAR Sci Resources, Camino Bajo Castillo S-N, Madrid 28692, Spain.
    von Essen, C.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.
    Voss, H.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Votruba, V.
    Acad Sci Czech Republ, Astron Inst, Fricova 298, Ondrejov 25165, Czech Republic.
    Voutsinas, S.
    Univ Edinburgh, Royal Observ, Inst Astron, Blackford Hill, Edinburgh EH9 3HJ, Midlothian, Scotland.
    Walmsley, G.
    CNES Ctr Spatial Toulouse, 18 Ave Edouard Belin, F-31401 Toulouse 9, France.
    Weiler, M.
    Univ Barcelona, Inst Ciencies Cosmos, IEEC UB, Marti I Franques 1, Barcelona 08028, Spain.
    Wertz, O.
    Sorbonne Univ, UPMC Univ, Paris 6 & CNRS, UMR 7095,Inst Astrophys Paris, 98 Bis Bd Arago, F-75014 Paris, France.
    Wevers, T.
    Radboud Univ Nijmegen, Dept Astrophys, IMAPP, POB 9010, NL-6500 GL Nijmegen, Netherlands;Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Wyrzykowski, L.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England;Univ Warsaw Observ, Al Ujazdowskie 4, PL-00478 Warsaw, Poland.
    Yoldas, A.
    Univ Cambridge, Inst Astron, Madingley Rd, Cambridge CB3 0HA, England.
    Zerjal, M.
    Tel Aviv Univ, Dept Geosci, IL-6997801 Tel Aviv, Israel;Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia.
    Ziaeepour, H.
    Univ Bourgogne Franche Comte, Inst UTINAM UMR6213, CNRS, OSU THETA Franche Comte Bourgogne, F-25000 Besancon, France.
    Zorec, J.
    Zschocke, S.
    Tech Univ Dresden, Lohrmann Observ, Mommsenstr 13, D-01062 Dresden, Germany.
    Zucker, S.
    Zurbach, C.
    Univ Montpellier, Lab Univ & Particules Montpellier, Pl Eugene Bataillon,CC72, F-34095 Montpellier 05, France.
    Zwitter, T.
    Univ Ljubljana, Fac Math & Phys, Jadranska Ulica 19, Ljubljana 1000, Slovenia.
    Observational Hertzsprung-Russell diagrams2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 616, article id A10Article in journal (Refereed)
    Abstract [en]

    Context. Gaia Data Release 2 provides high-precision astrometry and three-band photometry for about 1.3 billion sources over the full sky. The precision, accuracy, and homogeneity of both astrometry and photometry are unprecedented. Aims. We highlight the power of the Gaia DR2 in studying many fine structures of the Hertzsprung-Russell diagram (HRD). Gaia allows us to present many different HRDs, depending in particular on stellar population selections. We do not aim here for completeness in terms of types of stars or stellar evolutionary aspects. Instead, we have chosen several illustrative examples. Methods. We describe some of the selections that can be made in Gaia DR2 to highlight the main structures of the Gaia HRDs. We select both field and cluster (open and globular) stars, compare the observations with previous classifications and with stellar evolutionary tracks, and we present variations of the Gaia HRD with age, metallicity, and kinematics. Late stages of stellar evolution such as hot subdwarfs, post-AGB stars, planetary nebulae, and white dwarfs are also analysed, as well as low-mass brown dwarf objects. Results. The Gaia HRDs are unprecedented in both precision and coverage of the various Milky Way stellar populations and stellar evolutionary phases. Many fine structures of the HRDs are presented. The clear split of the white dwarf sequence into hydrogen and helium white dwarfs is presented for the first time in an HRD. The relation between kinematics and the HRD is nicely illustrated. Two different populations in a classical kinematic selection of the halo are unambiguously identified in the HRD. Membership and mean parameters for a selected list of open clusters are provided. They allow drawing very detailed cluster sequences, highlighting fine structures, and providing extremely precise empirical isochrones that will lead to more insight in stellar physics. Conclusions. Gaia DR2 demonstrates the potential of combining precise astrometry and photometry for large samples for studies in stellar evolution and stellar population and opens an entire new area for HRD-based studies.

  • 17.
    Bancelin, D.
    et al.
    Univ Vienna, Inst Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
    Nordlander, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2511, Australia.
    Pilat-Lohinger, E.
    Univ Vienna, Inst Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
    Loibnegger, B.
    Univ Vienna, Inst Astrophys, Turkenschanzstr 17, A-1180 Vienna, Austria.
    Dynamics of passing-stars-perturbed binary star systems2019In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 486, no 4, p. 4773-4780Article in journal (Refereed)
    Abstract [en]

    In this work, we investigate the dynamical effects of a sequence of close encounters over 200 Myr varying in the interval of 10 000-100 000 au between a binary star system and passing stars with masses ranging from 0.1 to 10 M-circle dot. We focus on binaries consisting of two Sun-like stars with various orbital separations a(0) from 50 to 200 au initially on circular planar orbits. We treat the probletn statistically since each sequence is clotted 1000 dines. Our study shows that orbits of binaries initially at a(0) = 50 au will slightly be perturbed by each close encounter and exhibit a small deviation in eccentricity (+0.03) and in periapsis distance (+1 and -2 au) around the mean value, However increasing a(0) will drastically increase these variances: up to +0.45 in eccentricity and between +63 and -106 au in periapsis, leading to a higher rate of disrupted binaries up to 50 per cent after the sequence of close encounters. Even though the secondary star can remain bound to the primary, similar to 20 per cent of the final orbits will have inclinations greater than 10 degrees. As planetary formation already takes place when stars are still members of their birth cluster, we show that the variances in eccentricity and periapsis distance of Jupiter- and Saturn-like planets will inversely decrease with a(0) after successive fly-bys. This leads to higher ejection rate at a(0) = 50 au but to a higher extent for Saturn-likes (60 percent) as those planets' apoapsis distances cross the critical stability distance for such binary separation.

  • 18.
    Barklem, Paul
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Excitation and charge transfer in low-energy hydrogen atom collisions with neutral oxygen2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 610, article id A57Article in journal (Refereed)
    Abstract [en]

    Excitation and charge transfer in low-energy O+H collisions is studied; it is a problem of importance for modelling stellar spectra and obtaining accurate oxygen abundances in late-type stars including the Sun. The collisions have been studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals (LCAO) model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multichannel Landau-Zener model. The method has been extended to include configurations involving excited states of hydrogen using an estimate for the two-electron transition coupling, but this extension was found to not lead to any remarkably high rates. Rate coefficients are calculated for temperatures in the range 1000-20000 K, and charge transfer and (de) excitation processes involving the first excited S-states, 4s.S-5(0) and 4s.S-3(0), are found to have the highest rates.

  • 19.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Dickinson, A. S.
    Gadea, F. X.
    Inelastic Na+H collision data for non-LTE applications in stellar atmospheres2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 519, p. A20-Article in journal (Refereed)
    Abstract [en]

    Rate coefficients for inelastic Na+H collisions are calculated for all transitions between the ten levels up to and including the ionic state (ion-pair production), namely Na(3s,3p,4s,3d,4p,5s,4d,4f,5p)+H(1s) and Na++H-. The calculations are based on recent full quantum scattering cross-section calculations. The data are needed for non-LTE applications in cool astrophysical environments, especially cool stellar atmospheres, and are presented for a temperature range of 500-8000 K. From consideration of the sensitivity of the cross-sections to input quantum chemical data and the results of different methods for the scattering calculations, a measure of the possible uncertainties in the rate coefficients is estimated.

  • 20.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Guitou, M.
    Feautrier, N.
    Gadea, F. X.
    Spielfiedel, A.
    On inelastic hydrogen atom collisions in stellar atmospheres2011In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 530, p. A94-Article in journal (Refereed)
    Abstract [en]

    The influence of inelastic hydrogen atom collisions on non-LTE spectral line formation has been, and remains to be, a significant source of uncertainty for stellar abundance analyses, due to the difficulty in obtaining accurate data for low-energy atomic collisions either experimentally or theoretically. For lack of a better alternative, the classical "Drawin formula" is often used. Over recent decades, our understanding of these collisions has improved markedly, predominantly through a number of detailed quantum mechanical calculations. In this paper, the Drawin formula is compared with the quantum mechanical calculations both in terms of the underlying physics and the resulting rate coefficients. It is shown that the Drawin formula does not contain the essential physics behind direct excitation by H atom collisions, the important physical mechanism being quantum mechanical in character. Quantitatively, the Drawin formula compares poorly with the results of the available quantum mechanical calculations, usually significantly overestimating the collision rates by amounts that vary markedly between transitions.

  • 21.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Belyaev, A. K.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Spielfiedel, A.
    Guitou, M.
    Feautrier, N.
    Inelastic Mg plus H collision data for non-LTE applications in stellar atmospheres2012In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 541, p. A80-Article in journal (Refereed)
    Abstract [en]

    Rate coefficients for inelastic Mg+H collisions are calculated for all transitions between the lowest seven levels and the ionic state (charge transfer), namely Mg(3s(2) S-1, 3s3p P-3, 3s3p P-1, 3s4s S-3, 3s4s S-1, 3s3d D-1, 3s4p P-3)+H(1s) and Mg+(3s S-2)+H-. The rate coefficients are based on cross-sections from full quantum scattering calculations, which are themselves based on detailed quantum chemical calculations for the MgH molecule. The data are needed for non-LTE applications in cool astrophysical environments, especially cool stellar atmospheres, and are presented for a temperature range of 500-8000 K. From consideration of the sensitivity of the cross-sections to various uncertainties in the calculations, most importantly input quantum chemical data and the numerical accuracy of the scattering calculations, a measure of the possible uncertainties in the rate coefficients is estimated.

  • 22.
    Barklem, Paul
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Osorio, Y.
    Instituto de Astrofísica de Canarias, vía Láctea.; Universidad de La Laguna, Departamento de Astrofísica.; Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg.
    Fursa, D. V.
    Curtin Institute for Computation, Kent Street.; Department of Physics, Astronomy and Medical Radiation Science, Kent Street.
    Bray, I.
    Curtin Institute for Computation, Kent Street.; Department of Physics, Astronomy and Medical Radiation Science, Kent Street.
    Zatsarinny, O.
    Drake University, Department of Physics and Astronomy.
    Bartschat, K.
    Drake University, Department of Physics and Astronomy.
    Jerkstrand, A.
    Max-Planck Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching.
    Inelastic e plus Mg collision data and its impact on modelling stellar and supernova spectra2017In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 606, article id A11Article in journal (Refereed)
    Abstract [en]

    Results of calculations for inelastic e+Mg effective collision strengths for the lowest 25 physical states of Mg I (up to 3s6p P-1), and thus 300 transitions, from the convergent close-coupling (CCC) and the B-spline R-matrix (BSR) methods are presented. At temperatures of interest, similar to 5000 K, the results of the two calculations differ on average by only 4%,with a scatter of 27%. As the methods are independent, this suggests that the calculations provide datasets for e+Mg collisions accurate to this level. Comparison with the commonly used dataset compiled by Mauas et al. (1988, ApJ, 330, 1008), covering 25 transitions among 12 states, suggests the Mauas et al. data are on average similar to 57% too low, and with a very large scatter of a factor of similar to 6.5. In particular the collision strength for the transition corresponding to the Mg I intercombination line at 457 nm is significantly underestimated by Mauas et al., which has consequences for models that employ this dataset. In giant stars the new data leads to a stronger line compared to previous non-LTE calculations, and thus a reduction in the non-LTE abundance correction by similar to 0.1 dex (similar to 25%). A non-LTE calculation in a supernova ejecta model shows this line becomes significantly stronger, by a factor of around two, alleviating the discrepancy where the 457 nm line in typical models with Mg/O ratios close to solar tended to be too weak compared to observations.

  • 23.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Accurate abundance analysis of late-type stars: advances in atomic physics2016In: The Astronomy and Astrophysics Review, ISSN 0935-4956, E-ISSN 1432-0754, Vol. 24, article id 9Article, review/survey (Refereed)
    Abstract [en]

    The measurement of stellar properties such as chemical compositions, masses and ages, through stellar spectra, is a fundamental problem in astrophysics. Progress in the understanding, calculation and measurement of atomic properties and processes relevant to the high-accuracy analysis of F-, G-, and K-type stellar spectra is reviewed, with particular emphasis on abundance analysis. This includes fundamental atomic data such as energy levels, wavelengths, and transition probabilities, as well as processes of photoionisation, collisional broadening and inelastic collisions. A recurring theme throughout the review is the interplay between theoretical atomic physics, laboratory measurements, and astrophysical modelling, all of which contribute to our understanding of atoms and atomic processes, as well as to modelling stellar spectra.

  • 24.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Excitation and charge transfer in low-energy hydrogen atom collisions with neutral iron2018In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 612, article id A90Article in journal (Refereed)
    Abstract [en]

    Data for inelastic processes due to hydrogen atom collisions with iron are needed for accurate modelling of the iron spectrum in late-type stars. Excitation and charge transfer in low-energy Fe+H collisions is studied theoretically using a previously presented method based on an asymptotic two-electron linear combination of atomic orbitals model of ionic-covalent interactions in the neutral atom-hydrogen-atom system, together with the multi-channel Landau-Zener model. An extensive calculation including 166 covalent states and 25 ionic states is presented and rate coefficients are calculated for temperatures in the range 1000-20 000 K. The largest rates are found for charge transfer processes to and from two clusters of states around 6.3 and 6.6 eV excitation, corresponding in both cases to active 4d and 5p electrons undergoing transfer. Excitation and de-excitation processes among these two sets of states are also significant.

  • 25.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Excitation and charge transfer in low-energy hydrogen-atom collisions with neutral atoms: Theory, comparisons, and application to Ca2016In: PHYSICAL REVIEW A, ISSN 2469-9926, Vol. 93, no 4, article id 042705Article in journal (Refereed)
    Abstract [en]

    A theoretical method is presented for the estimation of cross sections and rates for excitation and charge-transfer processes in low-energy hydrogen-atom collisions with neutral atoms, based on an asymptotic two-electron model of ionic-covalent interactions in the neutral atom-hydrogen-atom system. The calculation of potentials and nonadiabatic radial couplings using the method is demonstrated. The potentials are used together with the multichannel Landau-Zener model to calculate cross sections and rate coefficients. The main feature of the method is that it employs asymptotically exact atomic wave functions, which can be determined from known atomic parameters. The method is applied to Li + H, Na + H, and Mg + H collisions, and the results compare well with existing detailed full-quantum calculations. The method is applied to the astrophysically important problem of Ca + H collisions, and rate coefficients are calculated for temperatures in the range 1000-20 000 K.

  • 26.
    Barklem, Paul S.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Hydrogen Atom Collision Processes in Cool Stellar Atmospheres: Effects on Spectral Line Strengths and Measured Chemical Abundances in Old Stars2012In: XXI INTERNATIONAL CONFERENCE ON SPECTRAL LINE SHAPES (ICSLS 2012), 2012, p. 012049-Conference paper (Refereed)
    Abstract [en]

    The precise measurement of the chemical composition of stars is a fundamental problem relevant to many areas of astrophysics. State-of-the-art approaches attempt to unite accurate descriptions of microphysics, non-local thermodynamic equilibrium (non-LTE) line formation and 3D hydrodynamical model atmospheres. In this paper I review progress in understanding inelastic collisions of hydrogen atoms with other species and their influence on spectral line formation and derived abundances in stellar atmospheres. These collisions are a major source of uncertainty in non-LTE modelling of spectral lines and abundance determinations, especially for old, metal-poor stars, which are unique tracers of the early evolution of our galaxy. Full quantum scattering calculations of direct excitation processes X(nl) + H <-> X(n'l') + H and charge transfer processes X(nl) + H <-> X+ + H- have been done for Li, Na and Mg [1,2,3] based on detailed quantum chemical data, e.g. [4]. Rate coefficients have been calculated and applied to non-LTE modelling of spectral lines in stellar atmospheres [5,6,7,8,9]. In all cases we find that charge transfer processes from the first excited S-state are very important, and the processes affect measured abundances for Li, Na and Mg in some stars by as much as 60%. Effects vary with stellar parameters (e.g. temperature, luminosity, metal content) and so these processes are important not only for accurate absolute abundances, but also for relative abundances among dissimilar stars.

  • 27.
    Barklem, Paul S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Observational Astronomy. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Collet, R.
    Australian Natl Univ, Res Sch Astron & Astrophys, Canberra, ACT 2611, Australia.;Aarhus Univ, Dept Phys & Astron, Stellar Astrophys Ctr, Ny Munkegade 120, DK-8000 Aarhus C, Denmark..
    Partition functions and equilibrium constants for diatomic molecules and atoms of astrophysical interest2016In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 588, article id A96Article in journal (Refereed)
    Abstract [en]

    Partition functions and dissociation equilibrium constants are presented for 291 diatomic molecules for temperatures in the range from near absolute zero to 10 000 K, thus providing data for many diatomic molecules of astrophysical interest at low temperature. The calculations are based on molecular spectroscopic data from the book of Huber & Herzberg (1979, Constants of Diatomic Molecules) with significant improvements from the literature, especially updated data for ground states of many of the most important molecules by Irikura (2007, J. Phys. Chem. Ref. Data, 36, 389). Dissociation energies are collated from compilations of experimental and theoretical values. Partition functions for 284 species of atoms for all elements from H to U are also presented based on data collected at NIST. The calculated data are expected to be useful for modelling a range of low density astrophysical environments, especially star-forming regions, protoplanetary disks, the interstellar medium, and planetary and cool stellar atmospheres. The input data, which will be made available electronically, also provides a possible foundation for future improvement by the community.

  • 28.
    Barklem, Paul S.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics.
    Osorio, Yeisson Fabian Martinez
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Modelling the spectrum of Mg in cool stars2014In: XXII International Conference on Spectral Line Shapes (ICSLS 2014), 2014, p. 012001-, article id 012001Conference paper (Refereed)
    Abstract [en]

    The astrophysical importance of Mg, together with its unique range of spectral features in late-type stars, plus its relative simplicity from an atomic physics point of view, makes it a prime target and test bed for detailed ab initio non-local thermodynamic equilibrium (NLTE) modelling in stellar atmospheres. In this paper, we present example first results for calculations of NLTE Mg line based on a new model atom with significant improvements in the collision data for neutral Mg. We perform calculations for excitation of the lower-lying levels due to electron impacts using the R-matrix method. Recent data for excitation and charge transfer due to hydrogen atom impacts involving low-lying levels are now employed. Further, we have made efforts to use physically-motivated methods for calculating radiative and collisional data involving Rydberg states. The results are compared with observed spectra and the impact of the new calculations briefly explored.

  • 29.
    Barklem, Paul S.