The phase function and density of the dust observed at comet 67P/Churyumov–Gerasimenko

Marco Fulle (1, 2) , Ivano Bertini (3, 2) , Vincenzo Della Corte (4, 5, 2) , Carsten Güttler (6, 2) , Stavro L. Ivanovski (5, 4, 2) , Florangela La Forgia (3, 2) , Jérémie Lasue (7, 2) , Anny Chantal Levasseur-Regourd (8, 2) , Francesco Marzari (3, 2) , Fernando Moreno (9, 2) , Stefano Mottola (10, 2) , Giampiero Naletto (11, 3, 2) , Pasquale Palumbo (5, 2) , Giovanna Rinaldi (4, 5, 2) , Alessandra Rotundi (5, 4, 2) , Holger Sierks (6, 2) , Cesare Barbieri (2, 3) , Philippe Lamy (12, 8) , Rafael Rodrigo (13, 14) , Detlef Koschny (15) , Hans Rickman (16, 17) , Maria Antonella Barucci (18) , Jean-Loup Bertaux (8) , Dennis Bodewits (19) , Gabriele Cremonese (20) , Vania da Deppo (21) , Björn Davidsson (22) , Stefano Debei (23) , Mariolino de Cecco (24) , Jakob Deller (6) , Sonia Fornasier (18) , Olivier Groussin (12) , Pedro J. Gutiérrez (9) , Stubbe F. Hviid (10) , Wing-Huen Ip (25, 26) , Laurent Jorda (12) , Horst Uwe Keller (10, 27) , Jörg Knollenberg (10) , J. Rainer Kramm (6) , Ekkehard Kührt (10) , Michael Kuppers (28) , Luisa Maria Lara (9) , Monica Lazzarin (3) , José Juan Lopez-Moreno (9) , Xian Shi (6) , Nicholas Thomas (29) , Cécilia Tubiana (6)

1 OAT - INAF - Osservatorio Astronomico di Trieste
2 GSI - Helmholtz zentrum für Schwerionenforschung GmbH
3 Dipartimento di Fisica e Astronomia "Galileo Galilei"
4 IAPS - Istituto di Astrofisica e Planetologia Spaziali - INAF
5 DIST - Dipartimento di Scienze e Tecnologie [Napoli]
6 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
7 IRAP - Institut de recherche en astrophysique et planétologie
8 PLANETO - LATMOS
9 IAA - Instituto de Astrofísica de Andalucía
10 DLR Institut für Planetenforschung
11 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
12 LAM - Laboratoire d'Astrophysique de Marseille
13 CAB - Centro de Astrobiologia [Madrid]
14 ISSI - International Space Science Institute [Bern]
15 ESTEC - European Space Research and Technology Centre
16 Department of Physics and Astronomy [Uppsala]
17 CBK - Space Research Centre of Polish Academy of Sciences
18 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
19 Department of Astronomy [College Park]
20 OAPD - INAF - Osservatorio Astronomico di Padova
21 LUXOR - Laboratory for Ultraviolet and X-ray Optical Research [Padova]
22 JPL - Jet Propulsion Laboratory
23 Department of Industrial Engineering [Padova]
24 UNITN - Università degli Studi di Trento = University of Trento
25 Institute of Space Science [Taiwan]
26 SSI - Space Science Institute [Macau]
27 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
28 ESAC - European Space Astronomy Centre
29 Physikalisches Institut [Bern]

The OSIRIS camera onboard Rosetta measured the phase function of both the coma dust and the nucleus. The two functions have a very different slope versus the phase angle. Here, we show that the nucleus phase function should be adopted to convert the brightness to the size of dust particles larger than 2.5 mm only. This makes the dust bursts observed close to Rosetta by OSIRIS, occurring about every hour, consistent with the fragmentation on impact with Rosetta of parent particles, whose flux agrees with the dust flux observed by GIADA. OSIRIS also measured the antisunward acceleration of the fragments, thus providing the first direct measurement of the solar radiation force acting on the dust fragments and thus of their bulk density, excluding any measurable rocket effect by the ice sublimation from the dust. The obtained particle density distribution has a peak matching the bulk density of most COSIMA particles, and represents a subset of the density distribution measured by GIADA. This implies a bias in the elemental abundances measured by COSIMA, which thus are consistent with the 67P dust mass fractions inferred by GIADA, i.e. (38 ± 8) per cent of hydrocarbons versus the (62 ± 8) per cent of sulphides and silicates.

Domaines: Planète et Univers [physics]

Marco Fulle, Ivano Bertini, Vincenzo Della Corte, Carsten Güttler, Stavro L. Ivanovski, et al.. The phase function and density of the dust observed at comet 67P/Churyumov–Gerasimenko. Monthly Notices of the Royal Astronomical Society, 2018, 476 (2), pp.2835-2839. ⟨10.1093/mnras/sty464⟩. ⟨hal-02108705⟩