Thermal modelling of water activity on comet 67P/Churyumov-Gerasimenko with global dust mantle and plural dust-to-ice ratio

Xuanyu Hu (1, 2) , Xian Shi (1) , Holger Sierks (1) , Jürgen Blum (2) , Jürgen Oberst (3, 4, 5) , Marco Fulle (6) , Ekkehard Kührt (7) , Carsten Güttler (1) , Bastian Gundlach (2) , Horst Uwe Keller (2, 7) , Stefano Mottola (7) , Maurizio Pajola (8) , Cesare Barbieri (9) , Philippe L. Lamy (10) , Rafael Rodrigo (11, 12) , Detlef Koschny (13) , Hans Rickman (14, 15) , Jessica Agarwal (1) , Michael F. A'Hearn (16) , Maria Antonella Barucci (17) , Jean-Loup Bertaux (18) , Ivano Bertini (9) , Steve Boudreault (1) , Irene Büttner (1) , Gabriele Cremonese (19) , Vania da Deppo (20) , Björn Davidsson (21) , Stefano Debei (22) , Mariolino de Cecco (23) , Jakob Deller (1) , Sonia Fornasier (17) , Olivier Groussin (10) , Pedro J. Gutiérrez (24) , Pablo Gutiérrez-Marqués (1) , Ian Hall (1) , Marc Hofmann (1) , Stubbe F. Hviid (25) , Wing-Huen Ip (26) , Laurent Jorda (10) , Jörg Knollenberg (7) , Gabor Kovacs (1) , J.-Rainer Kramm (1) , Michael Küppers (27) , Luisa M. Lara (24) , Monica Lazzarin (9) , José J. López-Moreno (24) , Francesco Marzari (9) , Giampiero Naletto (28, 20, 29) , Nilda Oklay (7) , Michael L. Richards (1) , Joachim Ripken (1) , Nicolas Thomas (30, 31) , Cécilia Tubiana (1) , Jean-Baptiste Vincent (7)

1 MPS - Max-Planck-Institut für Sonnensystemforschung
2 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
3 TU - Technical University of Berlin / Technische Universität Berlin
4 Institut für Geodäsie und Geoinformationstechnik
5 MIIGAiK - Moscow State University of Geodesy and Cartography
6 OAT - INAF - Osservatorio Astronomico di Trieste
7 DLR Institut für Planetenforschung
8 ARC - NASA Ames Research Center
9 Dipartimento di Fisica e Astronomia "Galileo Galilei"
10 LAM - Laboratoire d'Astrophysique de Marseille
11 ISSI - International Space Science Institute [Bern]
12 CAB - Centro de Astrobiologia [Madrid]
13 ESTEC - European Space Research and Technology Centre
14 CBK - Space Research Centre of Polish Academy of Sciences
15 Department of Physics and Astronomy [Uppsala]
16 Department of Astronomy [College Park]
17 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
18 PLANETO - LATMOS
19 OAPD - INAF - Osservatorio Astronomico di Padova
20 IFN - CNR Institute for Photonics and Nanotechnologies
21 JPL - Jet Propulsion Laboratory
22 Department of Industrial Engineering [Padova]
23 University of Trento [Trento]
24 IAA - Instituto de Astrofísica de Andalucía
25 DLR Institute of Planetary Research
26 Institute of Space Science [Taiwan]
27 Operations Department (ESAC)
28 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
29 DEI - Department of Information Engineering [Padova]
30 Physikalisches Institut [Bern]
31 CSH - Center for Space and Habitability

We perform a thermo-physical analysis on water activity of comet 67P/Churyumov-Gerasimenko (67P). The sublimation of water is assumed to occur from beneath a global, desiccated dust mantle over the irregular-shaped nucleus. The concept of two thermal models, the recipe of model formulation and the strategy of application to comet 67P are described. For an accurate and efficient evaluation of energy input by insolation and self-heating over the nucleus, a Landscape data base is devised based on polyhedral shape models of the nucleus. We apply the thermal models to investigate the impact of certain parameters of nucleus properties on water production. It is found that the measured water production of 67P can be overall attributed to sublimation of water ice with a mass abundance of a few to 10 per cent beneath a uniform dust mantle of several millimetres to one centimetre in thickness. Insofar as 67P is concerned, we argue against the necessity to invoke assumptions on localized water activity, or on the distinction of active/dormant surface areas.

Keywords: 67P/Churyumov-Gerasimenko; Comets; Numerical methods; Refractory; Volatile

Domains: Earth and Planetary Astrophysics [astro-ph.EP]; Solar and Stellar Astrophysics [astro-ph.SR]; Physics [physics]; Astrophysics [astro-ph]

Xuanyu Hu, Xian Shi, Holger Sierks, Jürgen Blum, Jürgen Oberst, et al.. Thermal modelling of water activity on comet 67P/Churyumov-Gerasimenko with global dust mantle and plural dust-to-ice ratio. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S295 - S311. ⟨10.1093/mnras/stx1607⟩. ⟨insu-01574567⟩