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Variegation of comet 67P/Churyumov-Gerasimenko in regions showing activity
Max Planck Inst Sonnensyst Forsch, Justus von Liebig Weg 3, D-37077 Gottingen, Germany..
Univ Paris 06, Univ Paris 04, Sorbonne Paris Cite,PSL Res Univ, LESIA,Observ Paris,Univ Paris Diderot,CNRS, 5 Pl J Janssen, F-92195 Meudon, France..
Univ Padua, Ctr Studies & Act Space, CISAS G Colombo, Via Venezia 15, I-35131 Padua, Italy..
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2016 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 586, A80Article in journal (Refereed) PublishedText
Abstract [en]

Aims. We carried out an investigation of the surface variegation of comet 67P/Churyumov-Gerasimenko, the detection of regions showing activity, the determination of active and inactive surface regions of the comet with spectral methods, and the detection of fallback material. Methods. We analyzed multispectral data generated with Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) narrow angle camera (NAC) observations via spectral techniques, reflectance ratios, and spectral slopes in order to study active regions. We applied clustering analysis to the results of the reflectance ratios, and introduced the new technique of activity thresholds to detect areas potentially enriched in volatiles. Results. Local color inhomogeneities are detected over the investigated surface regions. Active regions, such as Hapi, the active pits of Seth and Ma'at, the clustered and isolated bright features in Imhotep, the alcoves in Seth and Ma'at, and the large alcove in Anuket, have bluer spectra than the overall surface. The spectra generated with OSIRIS NAC observations are dominated by cometary emissions of around 700 nm to 750 nm as a result of the coma between the comet's surface and the camera. One of the two isolated bright features in the Imhotep region displays an absorption band of around 700 nm, which probably indicates the existence of hydrated silicates. An absorption band with a center between 800-900 nm is tentatively observed in some regions of the nucleus surface. This absorption band can be explained by the crystal field absorption of Fe2+, which is a common spectral feature seen in silicates.

Place, publisher, year, edition, pages
2016. Vol. 586, A80
Keyword [en]
comets: individual: 67P/Churyumov-Gerasimenko, methods: data analysis, techniques: image processing, techniques: imaging spectroscopy
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:uu:diva-281833DOI: 10.1051/0004-6361/201527369ISI: 000369715900091OAI: oai:DiVA.org:uu-281833DiVA: diva2:917291
Swedish National Space Board
Available from: 2016-04-06 Created: 2016-03-30 Last updated: 2016-04-06Bibliographically approved

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Davidsson, Björn J. R.Rickman, Hans
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