Long term survival of surface water ice on comet 67P

Nilda Oklay 1 Stefano Mottola 1 Jean-Baptiste Vincent 1 Maurizio Pajola 2 Sonia Fornasier 3 Stubbe F. Hviid 1 David Kappel 1 Ekkehard Kührt 1 Horst Uwe Keller 4 Maria Antonella Barucci 3 Clément Feller 3 Frank Preusker 1 Frank Scholten 1 I. Hall 5 Holger Sierks 5 Cesare Barbieri 6 Philippe L. Lamy 7 Rafael Rodrigo 8, 9 Detlef Koschny 10 Hans Rickman 11, 12 Michael F. A’hearn 13 Jean-Loup Bertaux 14 Ivano Bertini 15 Dennis Bodewits 13 Gabriele Cremonese 16 Vania Da Deppo 17 Björn J. R. Davidsson 18 Stefano Debei 19 Mariolino De Cecco 20 Johannes Deller 5 J. D. P. Deshapriya 3 Marco Fulle 21 Adeline Gicquel 18 Olivier Groussin 7 Pedro J. Gutiérrez 22 Carsten Güttler 5 Pedro Henrique Hasselmann 3 M. Hofmann 5 W.-H. Ip 23 Laurent Jorda 7 J. Knollenberg 1 G. Kovacs 5 J.-R. Kramm 5 M. Küppers 24 Luisa M. Lara 22 M. Lazzarin 6 Z.-Y. Lin 23 J. J. Lopez Moreno 22 A. Lucchetti 16 F. Marzari 6 N. Masoumzadeh 5 G. Naletto 25, 15, 17 A. Pommerol 26 X. Shi 5 Nicholas Thomas 26 Cecilia Tubiana 5
Abstract : Numerous water-ice-rich deposits surviving more than several months on comet 67P/Churyumov-Gerasimenko were observed during the Rosetta mission. We announce the first-time detection of water ice features surviving up to two years since their first observation via OSIRIS NAC. Their existence on the nucleus of comet 67P at the arrival of the Rosetta spacecraft suggests that they were exposed to the surface during the comet’s previous orbit. We investigated the temporal variation of large water ice patches to understand the long-term sustainability of water ice on cometary nuclei on time scales of months and years. Large clusters are stable over typical periods of 0.5 year and reduce their size significantly around the comet’s perihelion passage, while small exposures disappear. We characterized the temporal variation of their multispectral signatures. In large clusters, dust jets were detected, whereas in large isolated ones no associated activity was detected. Our thermal analysis shows that the long-term sustainability of water-ice-rich features can be explained by the scarce energy input available at their locations over the first half year. However, the situation reverses for the period lasting several months around perihelion passage. Our two end-member mixing analysis estimates a pure water-ice equivalent thickness up to 15 cm within one isolated patch, and up to 2 m for the one still observable through the end of the mission. Our spectral modelling estimates up to 48% water-ice content for one of the large isolated feature, and up to 25% water ice on the large boulders located within clusters.
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Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2017, (in press). <10.1093/mnras/stx2298>
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Soumis le : mercredi 13 septembre 2017 - 22:25:33
Dernière modification le : vendredi 15 septembre 2017 - 01:10:20

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Nilda Oklay, Stefano Mottola, Jean-Baptiste Vincent, Maurizio Pajola, Sonia Fornasier, et al.. Long term survival of surface water ice on comet 67P. Monthly Notices of the Royal Astronomical Society, Oxford University Press (OUP): Policy P - Oxford Open Option A, 2017, (in press). <10.1093/mnras/stx2298>. <insu-01587261>

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