Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta.

Adeline Gicquel (1) , Jean-Baptiste Vincent (1) , Jessica Agarwal (1) , Michael F. A'Hearn (2) , Ivano Bertini (3) , Dennis Bodewits (2) , Holger Sierks (1) , Zhong-Yi Lin (4) , Cesara Barbieri (5) , Philippe Lamy (6) , Rafael Rodrigo (7, 8) , Detlief Koschny (9) , Hans Rickman (10, 11) , Horst Uwe Keller (12) , Maria Antonella Barucci (13) , Jean-Loup Bertaux (14) , S. Besse (15) , Gabriele Cremonese (16) , Vania da Deppo (17) , Björn Davidsson (11) , Stefano Debei (18) , Jakob Deller (1) , Mariolino de Cecco (19) , E. Frattin (16) , Mohamed Ramy El-Maarry (20) , Sonia Fornasier (13) , Marco Fulle (21) , O. Groussin (6) , Pedro J. Gutiérrez (22) , Pablo Gutiérrez-Marquez (1) , Carsten Güttler (1) , S. Höfner (1, 12) , Marc Hofmann (1) , X. Hu (1) , Stubbe F. Hviid (23) , Wing-Huen Ip (4) , Laurent Jorda (6) , J. Knollenberg (23) , G. Kovacs (24, 1) , J.-R. Kramm (1) , Ekkehard Kührt (23) , M. Küppers (25) , Luisa M. Lara (22) , Monica Lazzarin (5) , José J. Lopez Moreno (22) , S. Lowry (26) , F. Marzari (5) , N. Masoumzadeh (1) , M. Massironi (3) , F. Moreno (22) , S. Mottola (23) , Giampiero Naletto (3, 27, 17) , N. Oklay (1) , M. Pajola (3) , A. Pommerol (20) , Frank Preusker (23) , Frank Scholten (23) , X. Shi (1) , Nicolas Thomas (20) , I. Toth (6, 27) , Cécilia Tubiana (1)

1 MPS - Max-Planck-Institut für Sonnensystemforschung
2 Department of Astronomy [College Park]
3 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
4 Institute of Space Science [Taiwan]
5 Dipartimento di Fisica e Astronomia "Galileo Galilei"
6 LAM - Laboratoire d'Astrophysique de Marseille
7 CAB - Centro de Astrobiologia [Madrid]
8 ISSI - International Space Science Institute [Bern]
9 ESTEC - European Space Research and Technology Centre
10 CBK - Space Research Centre of Polish Academy of Sciences
11 Department of Physics and Astronomy [Uppsala]
12 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
13 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
14 PLANETO - LATMOS
15 RSSD - Research and Scientific Support Department, ESTEC
16 OAPD - INAF - Osservatorio Astronomico di Padova
17 IFN - CNR Institute for Photonics and Nanotechnologies
18 Department of Industrial Engineering [Padova]
19 University of Trento [Trento]
20 Physikalisches Institut [Bern]
21 OAT - INAF - Osservatorio Astronomico di Trieste
22 IAA - Instituto de Astrofísica de Andalucía
23 DLR Institut für Planetenforschung
24 MOMEI - Department of Mechatronics, Optics and Mechanical Engineering Informatics
25 Operations Department (ESAC)
26 CAPS - Centre for Astrophysics and Planetary Science [Canterbury]
27 DEI - Department of Information Engineering [Padova]

Beginning in March 2014, the OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) cameras began capturing images of the nucleus and coma (gas and dust) of comet 67P/Churyumov-Gerasimenko using both the wide angle camera (WAC) and the narrow angle camera (NAC). The many observations taken since July of 2014 have been used to study the morphology, location, and temporal variation of the comet’s dust jets. We analyzed the dust monitoring observations shortly after the southern vernal equinox on May 30 and 31, 2015 with the WAC at the heliocentric distance Rh = 1.53 AU, where it is possible to observe that the jet rotates with the nucleus. We found that the decline of brightness as a function of the distance of the jet is much steeper than the background coma, which is a first indication of sublimation. We adapted a model of sublimation of icy aggregates and studied the effect as a function of the physical properties of the aggregates (composition and size). The major finding of this article was that through the sublimation of the aggregates of dirty grains (radius a between 5μm and 50μm) we were able to completely reproduce the radial brightness profile of a jet beyond 4 km from the nucleus. To reproduce the data we needed to inject a number of aggregates between 8.5 × 1013 and 8.5 × 1010 for a = 5μm and 50μm respectively, or an initial mass of H2O ice around 22kg.

Keywords: observational method: numerical method; 67P/Churyumov-Gerasimenko; data analysis; comets

Domains: Sciences of the Universe [physics]; Astrophysics [astro-ph]; Earth and Planetary Astrophysics [astro-ph.EP]

Adeline Gicquel, Jean-Baptiste Vincent, Jessica Agarwal, Michael F. A'Hearn, Ivano Bertini, et al.. Sublimation of icy aggregates in the coma of comet 67P/Churyumov-Gerasimenko detected with the OSIRIS cameras on board Rosetta.. Monthly Notices of the Royal Astronomical Society, 2016, 462 (Suppl. 1), pp.S57-S66. ⟨10.1093/mnras/stw2117⟩. ⟨insu-01367966⟩