Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko

Björn Davidsson (1) , Pedro J. Gutiérrez (2) , Holger Sierks (3) , Cesare Barbieri (4, 5) , Philippe Lamy (6) , Rafael Rodrigo (7, 8) , Detlef Koschny (9) , Hans Rickman (10, 1) , Horst U. Keller (11) , Jessica Agarwal (3) , Michael F. A'Hearn (12, 13, 3) , Maria Antonietta Barucci (14) , Jean-Loup Bertaux (15) , Ivano Bertini (5) , Dennis Bodewits (13) , Gabriele Cremonese (16) , Vania da Deppo (17) , Stefano Debei (18) , Mariolino de Cecco (19) , Sonia Fornasier (14) , Marco Fulle (20) , Olivier Groussin (6) , Carsten Güttler (3) , Stubbe F. Hviid (21) , Wing-Huen Ip (22) , Laurent Jorda (6) , Jörg Knollenberg (21) , G. Kovacs (3) , J. Rainer Kramm (3) , Ekkehard Kührt (21) , Michael Küppers (23) , Fiorangela La Forgia (4) , Luisa M. Lara (2) , Monica Lazzarin (4) , Jose J. Lopez-Moreno (2) , S. Lowry (24) , Sara Magrin (4) , Francesco Marzari (4) , Harald Michalik (25) , R. Moissl–fraund (23) , Giampiero Naletto (18) , Nilda Oklay (3) , Maurizio Pajola (5) , Colin Snodgrass (26) , Nicholas Thomas (27) , Cecilia Tubiana (3) , Jean-Baptiste Vincent (3)

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

We investigate the dust coma within the Hill sphere of comet 67P/Churyumov-Gerasimenko. Aims. We aim to determine osculating orbital elements for individual distinguishable but unresolved slow-moving grains in the vicinity of the nucleus. In addition, we perform photometry and constrain grain sizes. Methods. We performed astrometry and photometry using images acquired by the OSIRIS Wide Angle Camera on the European Space Agency spacecraft Rosetta. Based on these measurements, we employed standard orbit determination and orbit improvement techniques. Results. Orbital elements and effective diameters of four grains were constrained, but we were unable to uniquely determine them. Two of the grains have light curves that indicate grain rotation. Conclusions. The four grains have diameters nominally in the range 0.14–0.50 m. For three of the grains, we found elliptic orbits, which is consistent with a cloud of bound particles around the nucleus. However, hyperbolic escape trajectories cannot be excluded for any of the grains, and for one grain this is the only known option. One grain may have originated from the surface shortly before observation. These results have possible implications for the understanding of the dispersal of the cloud of bound debris around comet nuclei, as well as for understanding the ejection of large grains far from the Sun.

Keywords: Celestial mechanics; Astrometry; 67P/Churyumov-Gerasimenko; Comets

Domains: Earth and Planetary Astrophysics [astro-ph.EP]

Björn Davidsson, Pedro J. Gutiérrez, Holger Sierks, Cesare Barbieri, Philippe Lamy, et al.. Orbital elements of the material surrounding comet 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics - A&A, 2015, 583, A16 (9 p.). ⟨10.1051/0004-6361/201525841⟩. ⟨insu-01202463⟩