Variegation of comet 67P/Churyumov-Gerasimenko in regions showing activity

Oklay, N.; Vincent, J. B.; Fornasier, S.; Pajola, M.; Besse, S.; Davidsson, B. J. R.; Lara, L. M.; Mottola, S.; Naletto, G.; Sierks, H.; Barucci, A. M.; Scholten, F.; Preusker, F.; Pommerol, Antoine; Masoumzadeh, N.; Lazzarin, M.; Barbieri, C.; Lamy, P. L.; Rodrigo, R.; Koschny, D.; ... (2016). Variegation of comet 67P/Churyumov-Gerasimenko in regions showing activity. Astronomy and astrophysics, 586(A80), A80. EDP Sciences 10.1051/0004-6361/201527369

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences

UniBE Contributor:

Pommerol, Antoine and Thomas, Nicolas

Subjects:

500 Science > 520 Astronomy
500 Science > 530 Physics

ISSN:

0004-6361

Publisher:

EDP Sciences

Language:

English

Submitter:

Katharina Weyeneth-Moser

Date Deposited:

22 Jun 2016 12:22

Last Modified:

26 Jun 2016 02:16

Publisher DOI:

10.1051/0004-6361/201527369

Web of Science ID:

000369715900091

BORIS DOI:

10.7892/boris.81939

URI:

https://boris.unibe.ch/id/eprint/81939

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