Multivariate statistical analysis of OSIRIS/Rosetta spectrophotometric data of comet 67P/Churyumov-Gerasimenko

Davide Perna 1 Marcello Fulchignoni 1 Maria Antonietta Barucci 1 Sonia Fornasier 1 Clément Feller 1 Prasanna Deshapriya 1 Pedro Henrique Hasselmann 1 Holder Sierks 2 Cesare Barbieri 3 Philippe L. Lamy 4 Rafael Rodrigo 5, 6 Detlef Koschny 7 Hans Rickman 8, 9 Michael F. A'Hearn 10 Jean-Loup Bertaux 11 Ivano Bertini 3 Gabriele Cremonese 12 Vania Da Deppo 13 Björn Davidsson 14 Stefano Debei 15 J. Deller 2 Mariolino De Cecco 16 Mohamed El-Maarry 17 Marco Fulle 18 Olivier Groussin 4 Pedro J. Gutierrez 19 Carsten Güttler 2 M. Hofmann 2 Stubbe F. Hviid Wing-Huen Ip 20 Laurent Jorda 4 Horst U. Keller 21, 22 Jörg Knollenberg 22 Rainer Kramm 2 Ekkerhard Kührt 22 Michael Küppers 23 Luisa-Maria Lara 19 Mario Lazzarin 3 José-Juan López-Moreno 19 Francesco Marzari 3 Giampiero Naletto 24, 13 Nilda Oklay 2 Nicholas Thomas 17 Cécilia Tubiana 2 Jean-Baptiste Vincent 2
Abstract : The ESA Rosetta mission explored comet 67P/Churyumov-Gerasimenko in 2014-2016, following its target before and after the perihelion passage on 13 August 2015. The NAC camera of the OSIRIS imaging system allowed to map the nucleus surface acquiring images with different filters in the visible wavelength range. Here we study the spectrophotometric behaviour of the nucleus by a multivariate statistical analysis, aiming to distinguish homogeneous groups and to constrain the bulk composition. We applied the G-mode clustering algorithm to 16 OSIRIS data cubes acquired on 5-6 August 2014 (mostly covering the northern hemisphere) and 2 May 2015 (mostly covering the southern hemisphere), selected to have complete coverage of the comet’s surface with similar observing conditions. We found four similar homogeneous groups for each of the analysed cubes. The first group corresponds to the average spectrophotometric behaviour of the nucleus. The second (spectrally redder) and the third (spectrally bluer) groups are found in regions that were already found to deviate from the average terrain of the comet by previous studies. A fourth group (characterised by enhancements of the flux at 700-750 nm and 989 nm, possibly due to H2O+ and/or NH2 emissions) seems connected with the cometary activity rather than with the bulk composition. While our aim in this work was to study the spectrophotometric behaviour of the nucleus of 67P/Churyumov-Gerasimenko as a whole, we found that a follow-up application of the G-mode to smaller regions of the surface could be useful in particular to identify and study the temporal evolution of ice patches, as well as to constrain the composition and physical processes behind the emission of dust jets.
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https://hal-insu.archives-ouvertes.fr/insu-01422872
Contributeur : Catherine Cardon <>
Soumis le : mardi 27 décembre 2016 - 15:58:01
Dernière modification le : jeudi 9 novembre 2017 - 09:36:02

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Davide Perna, Marcello Fulchignoni, Maria Antonietta Barucci, Sonia Fornasier, Clément Feller, et al.. Multivariate statistical analysis of OSIRIS/Rosetta spectrophotometric data of comet 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics - A&A, EDP Sciences, 2017, 600, A115 (9p.). 〈10.1051/0004-6361/201630015〉. 〈insu-01422872〉

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