Volume 591, July 2016
|Number of page(s)||10|
|Section||Planets and planetary systems|
|Published online||29 June 2016|
Physical properties and dynamical relation of the circular depressions on comet 67P/Churyumov-Gerasimenko
1 Institute of Astronomy, National Central University, 32054 Chung-Li, Taiwan
2 Institute of Space Sciences, National Central University, 32054 Chung-Li, Taiwan
3 Space Science Institute, Macau University of Science and Technology, Macau
4 Dept. of Earth Science, National Central University, 32054 Chung-Li, Taiwan
5 Max-Planck Institut für Sonnensystemforschung, Justus-von-Liebig-Weg, 3, 37077 Göttingen, Germany
6 Research and Scientific Support Department, European Space Agency, 2201 Noordwijk, The Netherlands
7 Department of Physics and Astronomy “G. Galilei”, University of Padova, Vic. Osservatorio 3, 35122 Padova, Italy
8 Centro di Ateneo di Studi ed Attivitá Spaziali “Giuseppe Colombo”, University of Padova, via Venezia 15, 35131 Padova, Italy
9 Aix-Marseille Université, CNRS, LAM (Laboratoire d’Astro-physique de Marseille) UMR 7326, 13388 Marseille, France
10 Centro de Astrobiologia (INTA-CSIC), Madrid, Spain
11 International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland
12 Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
13 PAS Space Research Center, Bartycka 18A, 00716 Warszawa, Poland
14 Institut für Geophysik und extraterrestrische Physik (IGEP), Technische Universität Braunschweig, 38106 Braunschweig, Germany
15 Department of Astronomy, University of Maryland, College Park, MD 20742-2421, USA
16 LESIA-Observatoire de Paris, CNRS, UPMC Univ. Paris 06, Univ. Paris-Diderot, 5 place J. Janssen, 92195 Meudon Principal Cedex, France
17 LATMOS, CNRS/UVSQ/IPSL, 11 boulevard d’Alembert, 78280 Guyancourt, France
18 INAF Osservatorio Astronomico di Padova, vic. dell Osservatorio 5, 35122 Padova, Italy
19 CNR-IFN UOS Padova LUXOR, via Trasea 7, 35131 Padova, Italy
20 Department of Industrial Engineering, University of Padova, via Venezia 1, 35131 Padova, Italy
21 University of Trento, via Sommarive 9, 38123 Trento, Italy
22 Physikalisches Institut, University of Bern, 3012 Bern, Switzerland
23 INAF – Osservatorio Astronomico di Trieste, via Tiepolo 11, 34143 Trieste, Italy
24 Instituto de Astrofísica de Andalucía (CSIC), c/Glorieta de la Astronomía, 18008 Granada, Spain
25 Deutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Planetenforschung, Rutherfordstrasse 2, 12489 Berlin, Germany
26 European Space Astronomy Centre (ESAC), PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
27 Centre for Astrophysics and Planetary Science, School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK
28 Southwest Research Institute, Boulder, CO, USA
29 Department of Information Engineering, University of Padova, via gradenigo 6/B, 35131 Padova, Italy
30 MTA CSFK Konkoly Observatory, 1121 Budapest, Hungary
Received: 19 January 2016
Accepted: 18 April 2016
Aims. We aim to characterize the circular depressions of comet 67P/Churyumov-Gerasimenko and investigate whether such surface morphology of a comet nucleus is related to the cumulative sublimation effect since becoming a Jupiter family comet (JFC).
Methods. The images from the Rosetta/OSIRIS science camera experiment are used to construct size frequency distributions of the circular depression structures on comet 67P and they are compared with those of the JFCs 81P/Wild 2, 9P/Tempel 1, and 103P/Hartley 2. The orbital evolutionary histories of these comets over the past 100 000 yr are analyzed statistically and compared with each other.
Results. The global distribution of the circular depressions over the surface of 67P is charted and classified. Descriptions are given to the characteristics and cumulative size frequency distribution of the identified features. Orbital statistics of the JFCs visited by spacecraft are derived.
Conclusions. The size frequency distribution of the circular depressions is found to have a similar power law distribution to those of 9P/Tempel 1 and 81P/Wild 2. This might imply that they could have been generated by the same process. Orbital integration calculation shows that the surface erosion histories of 81P/Wild 2, and 9P/Tempel 1 could be shorter than those of 67P, 103 P/Hartley 2 and 19P/Borrelly. From this point of view, the circular depressions could be dated back to the pre-JFC phase or the transneptunian phase of these comets. The north-south asymmetry in the distribution of the circular depressions could be associated with the heterogeneous structure of the nucleus of comet 67P and/or the solar insolation history.
Key words: comets: individual: 67P/Churyumov-Gerasimenko
© ESO, 2016
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