Modelling of the outburst on 2015 July 29 observed with OSIRIS cameras in the Southern hemisphere of comet 67P/Churyumov–Gerasimenko

Adeline Gicquel (1) , Martin Rose (2) , Jean-Baptiste Vincent (3) , Björn Davidsson (4) , Dennis Bodewits (5) , Michael F. A'Hearn (5) , Jessica Agarwal (1) , Nicolas Fougere (6) , Holger Sierks (1) , Ivano Bertini (7) , Zhong-Yi Lin (8) , Cesare Barbieri (9) , Philippe L. Lamy (10) , Rafael Rodrigo (11, 12) , Detlef Koschny (13) , Hans Rickman (14, 15) , Horst Uwe Keller (16) , Maria Antonella Barucci (17) , Jean-Loup Bertaux (18) , Sebastien Besse (19) , Steve Boudreault (1) , Gabriele Cremonese (20) , Vania da Deppo (21) , Stefano Debei (22) , Jakob Deller (1) , Mariolino de Cecco (23) , Elisa Frattin (20) , Mohamed Ramy El-Maarry (24) , Sonia Fornasier (17) , Marco Fulle (25) , Olivier Groussin (10) , Pedro J. Gutiérrez (26) , Pablo Gutiérrez-Marquez (1) , Carsten Güttler (1) , Sebastien Höfner (1) , Marc Hofmann (1) , Xuanyu Hu (1) , Stubbe F. Hviid (3) , Wing-Huen Ip (8) , Laurent Jorda (10) , Jörg Knollenberg (3) , Gabor Kovacs (27, 1) , J.-Rainer Kramm (1) , Ekkehard Kührt (3) , Michael Küppers (28) , Luisa M. Lara (26) , Monica Lazzarin (9) , José J. Lopez Moreno (26) , Stephen C. Lowry (29) , Francesco Marzari (9) , Nafiseh Masoumzadeh (1) , Matteo Massironi (7) , Fernando Moreno (26) , Stefano Mottola (3) , Giampiero Naletto (23, 7, 30) , Nilda Oklay (3) , Maurizio Pajola (31) , Frank Preusker (3) , Frank Scholten (3) , Xian Shi (1) , Nicolas Thomas (24) , Imre Toth (32, 10) , Cécilia Tubiana (1)

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

Images of the nucleus and the coma (gas and dust) of comet 67P/Churyumov– Gerasimenko have been acquired by the OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System) cameras since 2014 March using both the wide-angle camera and the narrow-angle camera (NAC). We use images from the NAC camera to study a bright outburst observed in the Southern hemisphere on 2015 July 29. The high spatial resolution of the NAC is needed to localize the source point of the outburst on the surface of the nucleus. The heliocentric distance is 1.25 au and the spacecraft–comet distance is 186 km. Aiming to better understand the physics that led to the outgassing, we used the Direct Simulation Monte Carlo method to study the gas flow close to the nucleus and the dust trajectories. The goal is to understand the mechanisms producing the outburst. We reproduce the opening angle of the outburst in the model and constrain the outgassing ratio between the outburst source and the local region. The outburst is in fact a combination of both gas and dust, in which the active surface is approximately 10 times more active than the average rate found in the surrounding areas. We need a number of dust particles 7.83 × 10¹¹ to 6.90 × 10¹⁵ (radius 1.97–185 μm), which correspond to a mass of dust (220–21) × 10³ kg.

Keywords: 67P/Churyumov; Data analysis; Numerical; Observations; Comets; Gerasimenko

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]; Physics [physics]; Astrophysics [astro-ph]

Adeline Gicquel, Martin Rose, Jean-Baptiste Vincent, Björn Davidsson, Dennis Bodewits, et al.. Modelling of the outburst on 2015 July 29 observed with OSIRIS cameras in the Southern hemisphere of comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S178 - S185. ⟨10.1093/mnras/stx1441⟩. ⟨insu-01574314⟩