Study of the characteristics of the grains in the coma background and in the jets in comet 67P/C-G, as observed by VIRTIS-M onboard of the Rosetta mission
Abstract
We report observations of the coma of the comet 67P/C-G performed in the near-IR by VIRTIS-M during the escort phase in April 2015. We selected observations performed when the spacecraft was at about 150 km from the nucleus, in order to cover the greatest part of the coma.We have chosen observations: a) with a diffuse coma without any evident strong jets and b) with strong jets originating from the “neck” region of the nucleus.We analyzed the in changes intensity and spectral behavior of the coma along the projected nucleocentric distance, for both the diffuse coma and for the jets.The results show that:- The emission of the grains in the diffuse coma is going as 1/rho in the FoV of VIRTIS, (about 2 km), suggesting the absence of grain fragmentation or sublimation. In the region close to the surface, within about 400 m, there is an increase of the emission, which is probably due to instrumental scattered light from the nucleus that can hide the effects due to the grains acceleration.- Also for the grains in the jets there is no evidence of fragmentation or sublimation in the spectral region where the scattering of the solar radiation is the mechanism of emission. Instead in the thermal region there are strong variations between the regions close to the nucleus and the farther ones.The authors would like to thank ASI (I), CNES (F), DLR (D), NASA (USA) for supporting this research. VIRTIS was built by a consortium formed by Italy, France and Germany, under the scientific responsibility of the “Istituto di Astrofisica e Planetologia Spaziale” of INAF (I), which guides also the scientific operations. The consortium includes also the “Laboratoire d'études spatiales et d'instrumentation en Astrophysique” of the Observatoire de Paris (F), and the “Institut für Planetenforschung” of DLR (D). The authors wish to thank the Rosetta Science Ground Segment and the Rosetta Mission Operations Centre of ESA for their continuous support.
- Publication:
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AAS/Division for Planetary Sciences Meeting Abstracts #47
- Pub Date:
- November 2015
- Bibcode:
- 2015DPS....4750307T