Dust mass distribution around comet 67P/Churyumov–Gerasimenko determined via parallax measurements using Rosetta's OSIRIS cameras

Theresa Ott (1) , Esther Drolshagen (2) , Detlef Koschny (3, 4) , Carsten Güttler (5) , Cécilia Tubiana (5) , Elisa Frattin (6, 7) , Jessica Agarwal (5) , Holger Sierks (5) , Ivano Bertini (7) , Cesare Barbieri (7) , Philippe Lamy (8) , Rafael Rodrigo (9, 10) , Hans Rickman (11, 12) , Michael F. A'Hearn (5, 13, 14) , Maria Antonella Barucci (15) , Jean-Loup Bertaux (16) , Steve Boudreault (5) , Gabriele Cremonese (6) , Vania da Deppo (17) , Björn Davidsson (14) , Stefano Debei (18) , Mariolino de Cecco (19) , Jakob Deller (5) , Clément Feller (15) , Sonia Fornasier (15) , Marco Fulle (20) , Bernhard Geiger (21) , Adeline Gicquel (5) , Olivier Groussin (8) , Pedro J. Gutiérrez (22) , Marc Hofmann (5) , Stubbe F. Hviid (23) , Wing-Huen Ip (24, 25) , Laurent Jorda (8) , Horst Uwe Keller (26, 23) , Jörg Knollenberg (23) , Gabor Kovacs (5) , J.-Rainer Kramm (5) , Ekkehard Kührt (23) , Michael Küppers (21) , Luisa M. Lara (22) , Monica Lazzarin (7) , Zhong-Yi Lin (25) , José J. López-Moreno (22) , Francesco Marzari (7) , Stefano Mottola (23) , Giampiero Naletto (27, 17, 28) , Nilda Oklay (23) , Maurizio Pajola (29) , X. Shi (5) , Nicolas Thomas (30) , Jean-Baptiste Vincent (23) , Björn Poppe (2)

1 University of Oldenburg
2 OFFIS - Carl Von Ossietzky Universität Oldenburg = Carl von Ossietzky University of Oldenburg
3 TUM - Technische Universität Munchen - Technical University Munich - Université Technique de Munich
4 ESTEC - European Space Research and Technology Centre
5 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
6 OAPD - INAF - Osservatorio Astronomico di Padova
7 Dipartimento di Fisica e Astronomia "Galileo Galilei"
8 LAM - Laboratoire d'Astrophysique de Marseille
9 ISSI - International Space Science Institute [Bern]
10 CAB - Centro de Astrobiologia [Madrid]
11 CBK - Space Research Centre of Polish Academy of Sciences
12 Department of Physics and Astronomy [Uppsala]
13 Department of Astronomy [College Park]
14 JPL - Jet Propulsion Laboratory
15 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
16 PLANETO - LATMOS
17 IFN - CNR Institute for Photonics and Nanotechnologies
18 Department of Industrial Engineering [Padova]
19 UNITN - Università degli Studi di Trento = University of Trento
20 OAT - INAF - Osservatorio Astronomico di Trieste
21 Operations Department (ESAC)
22 IAA - Instituto de Astrofísica de Andalucía
23 DLR Institut für Planetenforschung
24 SSI - Space Science Institute [Macau]
25 Institute of Space Science [Taiwan]
26 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
27 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
28 DEI - Department of Information Engineering [Padova]
29 ARC - NASA Ames Research Center
30 Physikalisches Institut [Bern]

The OSIRIS (optical, spectroscopic and infrared remote imaging system) instrument on board the ESA Rosetta spacecraft collected data of 67P/Churyumov–Gerasimenko for over 2 yr. OSIRIS consists of two cameras, a Narrow Angle Camera and a Wide Angle Camera. For specific imaging sequences related to the observation of dust aggregates in 67P's coma, the two cameras were operating simultaneously. The two cameras are mounted 0.7 m apart from each other, as a result this baseline yields a parallax shift of the apparent particle trails on the analysed images directly proportional to their distance. Thanks to such shifts, the distance between observed dust aggregates and the spacecraft was determined. This method works for particles closer than 6000 m to the spacecraft and requires very few assumptions. We found over 250 particles in a suitable distance range with sizes of some centimetres, masses in the range of 10⁻⁶–10² kg and a mean velocity of about 2.4 m s⁻¹ relative to the nucleus. Furthermore, the spectral slope was analysed showing a decrease in the median spectral slope of the particles with time. The further a particle is from the spacecraft the fainter is its signal. For this reason, this was counterbalanced by a debiasing. Moreover, the dust mass-loss rate of the nucleus could be computed as well as the Afρ of the comet around perihelion. The summed-up dust mass-loss rate for the mass bins 10⁻⁴–10² kg is almost 8300 kg s⁻¹.

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

Theresa Ott, Esther Drolshagen, Detlef Koschny, Carsten Güttler, Cécilia Tubiana, et al.. Dust mass distribution around comet 67P/Churyumov–Gerasimenko determined via parallax measurements using Rosetta's OSIRIS cameras. Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S276 - S284. ⟨10.1093/mnras/stx1419⟩. ⟨insu-01574533⟩