Detection of Exposed H2O ice on the Nucleus of Comet 67P/Churyumov-Gerasimenko

Since the orbital insertion of the Rosetta spacecraft, comet 67P/Churyumov-Gerasimenko (67P/C-G) has been mapped by OSIRIS camera and VIRTIS spectro-imager, producing a huge quantity of images and spectra of the comet's nucleus.

The aim of this work is to search for the presence of H2O on the nucleus which, in general, appears very dark and rich in dehydrated organic material. After selecting images of the bright spots which could be good candidates to search for H2O ice, taken at high resolution by OSIRIS, we check for spectral cubes of the selected coordinates to identify these spots observed by VIRTIS.

The selected OSIRIS images were processed with the OSIRIS standard pipeline and corrected for the illumination conditions for each pixel using the Lommel-Seeliger disk law. The spots with higher I/F were selected and then analysed spectrophotometrically and compared with the surrounding area. We selected 13 spots as good targets to be analysed by VIRTIS to search for the 2 micron absorption band of water ice in the VIRTIS spectral cubes. Out of the 13 selected bright spots, eight of them present positive H2O ice detection on the VIRTIS data.

A spectral analysis was performed and the approximate temperature of each spot was computed. The H2O ice content was confirmed by modeling the spectra with mixing (areal and intimate) of H2O ice and dark terrain, using Hapke's radiative transfer modeling. We also present a detailed analysis of the detected spots.

M.A. Barucci, G. Filacchione, S. Fornasier, A. Raponi, J.D.P. Deshapriya, F. Tosi, C. Feller, M.Ciarniello, H. Sierks, F. Capaccioni, A. Pommerol, M. Massironi, N. Oklay, F. Merlin, J.-B. Vincent, M. Fulchignoni, A. Guilbert-Lepoutre, D. Perna, M.T. Capria, P. H. Hasselmann, B. Rousseau, C. Barbieri, D. Bockelee-Morvan, P. L. Lamy, C. De Sanctis, R. Rodrigo, S. Erard, D. Koschny, C. Leyrat, H. Rickman, P. Drossart, H. U. Keller, M. F. A'Hearn, G. Arnold, J.-L. Bertaux, I. Bertini, P. Cerroni, G. Cremonese, V. Da Deppo, B. J. R. Davidsson, El-Maarry, S. Fonti, M. Fulle, O. Groussin, C. Guttler
(Submitted on 2 Sep 2016)

Comments: paper in press in A&A, 13 pages, 6 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
DOI: 10.1051/0004-6361/201628764
Cite as: arXiv:1609.00551 [astro-ph.EP] (or arXiv:1609.00551v1 [astro-ph.EP] for this version)
Submission history
From: Sonia Fornasier [view email]
[v1] Fri, 2 Sep 2016 11:30:59 GMT (4959kb,D)
http://arxiv.org/abs/1609.00551

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