Article Dans Une Revue Monthly Notices of the Royal Astronomical Society Année : 2017

The Opposition Effect of 67P/Churyumov-Gerasimenko on post-perihelion Rosetta images

1 LESIA - Laboratoire d'études spatiales et d'instrumentation en astrophysique
2 Physikalisches Institut [Bern]
3 MPS - Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research
4 Dipartimento di Fisica e Astronomia "Galileo Galilei"
5 LAM - Laboratoire d'Astrophysique de Marseille
6 CAB - Centro de Astrobiologia [Madrid]
7 ESTEC - European Space Research and Technology Centre
8 Department of Physics and Astronomy [Uppsala]
9 CBK - Space Research Centre of Polish Academy of Sciences
10 Department of Astronomy [College Park]
11 PLANETO - LATMOS
12 OAPD - INAF - Osservatorio Astronomico di Padova
13 IFN - CNR Institute for Photonics and Nanotechnologies
14 JPL - Jet Propulsion Laboratory
15 Department of Industrial Engineering [University of Padua]
16 UNITN - Università degli Studi di Trento = University of Trento
17 OAT - INAF - Osservatorio Astronomico di Trieste
18 PSI - Planetary Science Institute [Tucson]
19 IAA-CSIC - Instituto de Astrofísica de Andalucía = Institute of Astrophysics of Andalusia
20 DLR Institut für Planetenforschung
21 IANCU - Institute of Astronomy [Taiwan]
22 SSI - Space Science Institute [Macau]
23 AMU - Aix Marseille Université
24 IGEP - Institut für Geophysik und Extraterrestrische Physik [Braunschweig]
25 BME - Budapest University of Technology and Economics [Budapest]
26 ESAC - European Space Astronomy Centre
27 CISAS - Centro di Ateneo di Studi e Attività Spaziali “Giuseppe Colombo”
28 DEI - Department of Information Engineering [Padova]
Bernhard Jost
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  • PersonId : 1013428
Jean-Loup Bertaux
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  • PersonId : 914210
Laurent Jorda
Nilda Oklay
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  • PersonId : 976656
Nicolas Thomas
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  • PersonId : 963386
  • IdRef : 079933580

Résumé

High-resolution OSIRIS/Rosetta images of 67P/Churyumov-Gerasimenko acquired on the night run of April 9th to 10th 2016 shows, at large scale, an Opposition Effect (OE) spot swooping across Imhotep as the phase angle ranges from 0° to 17°. In this work, we fitted the phase curve of the whole surface imaged as well as three particular features using both linear-exponential and Hapke (2012) model. Those features encompass different types of spectral behaviour: a circular mesa, one venous structure and an assemble of bright spots, going from red to blue colours. Both Hapke and linear-exponential parameters indicate a stepwise sharpening of the OE from bright spots to circular mesa. Yet, a very broad non-linear phase curve is verified and no sign of sharp OE associated to coherent-backscattering mechanism observed. We estimate that 67P surface is dominated by opaque, desiccated and larger-than-wavelength irregular grains. Veins and bright spots display photometric properties consistent to surfaces becoming slightly brighter as it is enriched by high albedo ice grains. We also report the estimation of normal albedo for all cometary regions observed throughout the image sequence. Comparison to pre-perihelion results (Fornasier et al., 2015) indicates that far better insolation of northern brighter regions, i.e. Hapi, Hathor and Seth, is sufficient to explain mismatches on the photometric parameters. However, metre-scale photometric analysis of Imhotep-Ash boundary area (Feller et al., 2016) advocates for mild darkening (< 7%) of the surface at local scale.

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insu-01599000 , version 1 (09-05-2018)

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Pedro Henrique Hasselmann, Maria Antonella Barucci, Sonia Fornasier, Clément Feller, Prasanna Deshapriya, et al.. The Opposition Effect of 67P/Churyumov-Gerasimenko on post-perihelion Rosetta images . Monthly Notices of the Royal Astronomical Society, 2017, 469 (Suppl_2), pp.S550-S567. ⟨10.1093/mnras/stx1834⟩. ⟨insu-01599000⟩
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