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    Comet 67P/Churyumov-Gerasimenko: Constraints on its origin from OSIRIS observations

    Rickman, H. and Marchi, S. and A’Hearn, M.F. and Barbieri, C. and El-Maarry, Mohamed Ramy and Güttler, C. and Ip, W.-H. and Keller, H.U. and Lamy, P. and Marzari, F. and Massironi, M. and Naletto, G. and Pajola, M. and Sierks, H. and Koschny, D. and Rodrigo, R. and Barucci, M.A. and Bertaux, J.-L. and Bertini, I. and Cremonese, G. and Da Deppo, V. and Debei, S. and De Cecco, M. and Fornasier, S. and Fulle, M. and Groussin, O. and Gutiérrez, P.J. and Hviid, S.F. and Jorda, L. and Knollenberg, J. and Kramm, J.-R. and Kührt, E. and Küppers, M. and Lara, L.M. and Lazzarin, M. and Lopez Moreno, J.J. and Michalik, H. and Sabau, L. and Thomas, N. and Vincent, J.-B. and Wenzel, K.-P. (2015) Comet 67P/Churyumov-Gerasimenko: Constraints on its origin from OSIRIS observations. Astronomy & Astrophysics 583 , A44. ISSN 0004-6361.

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    Abstract

    Context. One of the main aims of the ESA Rosetta mission is to study the origin of the solar system by exploring comet 67P/Churyumov-Gerasimenko at close range. Aims. In this paper we discuss the origin and evolution of comet 67P/Churyumov-Gerasimenko in relation to that of comets in general and in the framework of current solar system formation models. Methods. We use data from the OSIRIS scientific cameras as basic constraints. In particular, we discuss the overall bi-lobate shape and the presence of key geological features, such as layers and fractures. We also treat the problem of collisional evolution of comet nuclei by a particle-in-a-box calculation for an estimate of the probability of survival for 67P/Churyumov-Gerasimenko during the early epochs of the solar system. Results. We argue that the two lobes of the 67P/Churyumov-Gerasimenko nucleus are derived from two distinct objects that have formed a contact binary via a gentle merger. The lobes are separate bodies, though sufficiently similar to have formed in the same environment. An estimate of the collisional rate in the primordial, trans-planetary disk shows that most comets of similar size to 67P/Churyumov-Gerasimenko are likely collisional fragments, although survival of primordial planetesimals cannot be excluded. Conclusions. A collisional origin of the contact binary is suggested, and the low bulk density of the aggregate and abundance of volatile species show that a very gentle merger must have occurred. We thus consider two main scenarios: the primordial accretion of planetesimals, and the re-accretion of fragments after an energetic impact onto a larger parent body. We point to the primordial signatures exhibited by 67P/Churyumov-Gerasimenko and other comet nuclei as critical tests of the collisional evolution.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): comets: individual: 67P/Churyumov-Gerasimenko
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 20 Nov 2018 14:21
    Last Modified: 20 Nov 2018 14:21
    URI: http://eprints.bbk.ac.uk/id/eprint/25202

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