Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov–Gerasimenko

Maurizio Pajola (1) , J.-C. Lee (2) , N. Oklay (3) , S. F. Hviid (4) , L. Penasa (5) , S. Mottola (4) , X. Shi (3) , Sonia Fornasier (6) , B. Davidsson (7) , L. Giacomini (8) , A. Lucchetti (1) , M. Massironi (9) , Jean-Baptiste Vincent (4) , I. Bertini (10) , G. Naletto (5, 10, 11) , W.-H. Ip (12, 13) , H. Sierks (3) , Philippe Lamy (14) , R. Rodrigo (15, 16) , D. Koschny (17) , H. U. Keller (4) , J. Agarwal (3) , M. A. Barucci (6) , Jean-Loup Bertaux (14, 18) , Dennis Bodewits (19) , P. Cambianica (5) , Gabriele Cremonese (1) , V. Da deppo (11) , S. Debei (20) , M. De cecco (21) , J. Deller (3) , M. R. El maarry (22) , C. Feller (6) , S. Ferrari (5) , M. Fulle (23) , P. J. Gutierrez (24) , C. Güttler (3) , Luisa M. Lara (24) , F. La forgia (10) , M. Lazzarin (10) , Z. Y. Lin (12) , J. J. Lopez moreno (24) , F. Marzari (10) , F. Preusker (4) , F. Scholten (4) , I. Toth (25) , Cécilia Tubiana (3)

1 OAPD - INAF - Osservatorio Astronomico di Padova
2 Department of Atmospheric Sciences [Taoyuan City]
3 MPS - Max-Planck-Institut für Sonnensystemforschung
4 DLR Institut für Planetenforschung
5 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
6 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
7 JPL - Jet Propulsion Laboratory
8 IAPS - Istituto di Astrofisica e Planetologia Spaziali - INAF
9 Dipartimento di Geoscienze [Padova]
10 Dipartimento di Fisica e Astronomia "Galileo Galilei"
11 IFN - CNR Istituto di Fotonica e Nanotecnologie [Padova]
12 Institute of Space Science [Taiwan]
13 SSI - Space Science Institute [Macau]
14 PLANETO - LATMOS
15 CAB - Centro de Astrobiologia [Madrid]
16 ISSI - International Space Science Institute [Bern]
17 ESTEC - European Space Research and Technology Centre
18 IKI - Space Research Institute of the Russian Academy of Sciences
19 Department of Physics [Auburn]
20 Department of Mechanical Engineering [Padova]
21 University of Trento [Trento]
22 LASP - Laboratory for Atmospheric and Space Physics [Boulder]
23 OAT - INAF - Osservatorio Astronomico di Trieste
24 IAA - Institut d'Astronomie et d'Astrophysique [Bruxelles]
25 Konkoly Observatory

By using the Rosetta/OSIRIS-NAC data set taken in 2014 August, we focus on the neck region, called Hapi, located on 67P Churyumov–Gerasimenko’s Northern hemisphere. The gravitational potential and slopes of Hapi, coupled with the geological unit identification and the boulder size–frequency distributions, support the interpretation that both taluses and gravitational accumulation deposits observable on Hapi are the result of multiple cliff collapses that occurred at different times. By contrast, the fine-particle deposits observable in the central part of the study area are made of aggregates coming from the Southern hemisphere and deposited during each perihelion passage. Both the consolidated terrains on the western part of Hapi, as well as the centrally aligned ridge made of boulder-like features, suggest that Hapi is in structural continuity with the onion-like structure of the main lobe of 67P. Despite the dusty blanket observable on Hapi, its terrains are characterized by water-ice-rich components that, once repeatedly and rapidly illuminated, sublimate, hence resulting in the strong jet activity observed in 2014 August.

Domains: Astrophysics [astro-ph]; Astrophysics [astro-ph]

Maurizio Pajola, J.-C. Lee, N. Oklay, S. F. Hviid, L. Penasa, et al.. Multidisciplinary analysis of the Hapi region located on Comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society, 2019, 485 (2), pp.2139-2154. ⟨10.1093/mnras/stz446⟩. ⟨insu-02114153⟩