Dust thermal properties in the coma of comet 67P/CG as observed by from Rosetta/VIRTIS

Thursday, 18 December 2014
Cedric Leyrat1, Dominique Bockelée-Morvan2, Stéphane Erard3, Fabrizio Capaccioni4, Gianrico Filacchione5, Gian Paolo Tozzi6 and Pierre Drossart3, (1)Paris Observatory Meudon, Meudon, France, (2)Paris Observatory, Paris, France, (3)LESIA Observatoire de Paris, Meudon, France, (4)Organization Not Listed, Washington, DC, United States, (5)IAPS-INAF, Rome, Italy, (6)INAF - Osservatorio Astrofisico di Arcetri, Firenze, Italy
In August 2014, the ESA’s Rosetta spacecraft has reached its final target, the comet 67P/Churyumov-Gerasimenko. The remote sensing instrument VIRTIS, composed of two channels –M for mapping and –H for high resolution has observed intensively both the nucleus and the coma environment, in the 0.3-5 microns wavelength domain. In addition to nucleus mapping observations, many observations sequences are dedicated to the coma, in order to get IR spectra of gas and dust.

Dust thermal emission should affect IR coma spectra by adding a continuum over which gas emission lines are detected. Depending on the amount of silicates or ices that compose the dust grains, absorption bands can also be detected in IR spectra. The dust infrared emission depends both on the size distribution of the grains and their chemical composition. We will present initial guesses of the dust thermal emission using simple thermal models, and we will compare them to the VIRTIS-H and –M spectra obtained since July 2014.

Authors acknowledge the funding from CNES French and ASI Italian Space Agencies.