Are fractured cliffs the source of cometary dust jets ? insights from OSIRIS/Rosetta at 67P/Churyumov-Gerasimenko

Jean-Baptiste Vincent (1) , Nilda Oklay (1) , Maurizio Pajola (2) , Sebastien Höfner (1, 3) , Holger Sierks (1) , X. Hu (1, 3) , Cesare Barbieri (4) , Philippe L. Lamy (5) , R. Rodrigo (6, 7) , Detlef Koschny (8) , Hans Rickman (9, 10) , Horst Uwe Keller (3) , Michael F. A'Hearn (11, 1, 12) , Maria A. Barucci (13) , Jean-Loup Bertaux (14) , I. Bertini (2) , S. Besse (8) , Dennis Bodewits (12) , Gabriele Cremonese (15) , Vania da Deppo (16) , B. Davidsson (10) , Stefano Debei (17) , M. de Cecco (18) , Mohamed R. El-Maarry (19) , Sonia Fornasier (13) , M. Fulle (20) , Olivier Groussin (5) , Pedro J. Gutiérrez (21) , P. Gutiérrez-Marquez (1) , C. Güttler (1) , M. Hofmann (1) , S. F. Hviid (22) , W. -H. Ip (23) , L. Jorda (5) , J. Knollenberg (22) , G. Kovacs (1, 24) , J. -R. Kramm (1) , Ekkehard Kührt (22) , M. Küppers (25) , L. M. Lara (21) , M. Lazzarin (4) , Z. -Y. Lin (23) , J. J. Lopez Moreno (21) , S. Lowry (26) , F. Marzari (4) , M. Massironi (2) , F. Moreno (21) , S. Mottola (22) , G. Naletto (2, 16, 27) , F. Preusker (22) , F. Scholten (22) , X. Shi (1) , Nicholas Thomas (19) , I. Toth (28, 5) , C. Tubiana (1)

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

Dust jets (i.e., fuzzy collimated streams of cometary material arising from the nucleus) have been observed in situ on all comets since the Giotto mission flew by comet 1P/Halley in 1986, and yet their formation mechanism remains unknown. Several solutions have been proposed involving either specific properties of the active areas or the local topography to create and focus the gas and dust flows. While the nucleus morphology seems to be responsible for the larger features, high resolution imagery has shown that broad streams are composed of many smaller jets (a few meters wide) that connect directly to the nucleus surface. Aims. We monitored these jets at high resolution and over several months to understand what the physical processes are that drive their formation and how this affects the surface. Methods. Using many images of the same areas with different viewing angles, we performed a 3-dimensional reconstruction of collimated jets and linked them precisely to their sources on the nucleus. Results. We show here observational evidence that the northern hemisphere jets of comet 67P/Churyumov-Gerasimenko arise from areas with sharp topographic changes and describe the physical processes involved. We propose a model in which active cliffs are the main source of jet-like features and therefore of the regions eroding the fastest on comets. We suggest that this is a common mechanism taking place on all comets.

Mots clés: Comets; 67P/Churyumov-Gerasimenko

Domaines: Planétologie et astrophysique de la terre [astro-ph.EP]; Astrophysique stellaire et solaire [astro-ph.SR]

Jean-Baptiste Vincent, Nilda Oklay, Maurizio Pajola, Sebastien Höfner, Holger Sierks, et al.. Are fractured cliffs the source of cometary dust jets ? insights from OSIRIS/Rosetta at 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics - A&A, 2016, 587 (March), A14 (15 p.). ⟨10.1051/0004-6361/201527159⟩. ⟨insu-01274339⟩