A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta

Joerg Knollenberg 1 Z. Y. Lin 2 S. F. Hviid 1 N. Oklay 3 J.-B. Vincent 3 D. Bodewits 4 S. Mottola 1 M. Pajola 5 H. Sierks 3 C. Barbieri 6 P. Lamy 7 R. Rodrigo 8, 9 D. Koschny 10 H. Rickman 11, 12 M. F. A'Hearn 4 M. A. Barucci 13 Jean-Loup Bertaux 14 I. Bertini 5 G. Cremonese 6 B. Davidsson 12 V. Da Deppo 15 S. Debei 16 M. De Cecco 17 S. Fornasier 13 M. Fulle 18 O. Groussin 7 P. J. Gutiérrez 19 W.-H. Ip 2 L. Jorda 7 H. U. Keller 20, 1 E. Kührt 1 J. R. Kramm 3 M. Küppers 21 L. M. Lara 19 M. Lazzarin 6 J. J. Lopez Moreno 19 F. Marzari 6 G. Naletto 22, 5, 15 N. Thomas 23 C. Güttler 3 F. Preusker 1 F. Scholten 1 C. Tubiana 3
Abstract : On 12 March 2015 the OSIRIS WAC camera onboard the ESA Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko observed a small outburst originating from the Imhotep region at the foot of the big lobe of the comet. These measurements are unique since it was the first time that the initial phase of a transient outburst event could be directly observed. Aims. We investigate the evolution of the dust jet in order to derive clues about the outburst source mechanism and the ejected dust particles, in particular the dust mass, dust-to-gas ratio and the particle size distribution. Methods. Analysis of the images and of the observation geometry using comet shape models in combination with gasdynamic modeling of the transient dust jet were the main tools used in this study. Synthetic images were computed for comparison with the observations. Results. Analysis of the geometry revealed that the source region was not illuminated until 1.5 h after the event implying true nightside activity was observed. The outburst lasted for less than one hour and the average dust production rate during the initial four minutes was of the order of 1 kg/s. During this time the outburst dust production rate was approximately constant, no sign for an initial explosion could be detected. For dust grains between 0.01-1 mm a power law size distribution characterized by an index of about 2.6 provides the best fit to the observed radiance profiles. The dust-to-gas ratio of the outburst jet is in the range 0.6-1.8.
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Astronomy and Astrophysics - A&A, EDP Sciences, 2016, 596, A89 (10 p.). <10.1051/0004-6361/201527744>
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Soumis le : dimanche 25 septembre 2016 - 14:33:19
Dernière modification le : mardi 30 mai 2017 - 01:19:29

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Joerg Knollenberg, Z. Y. Lin, S. F. Hviid, N. Oklay, J.-B. Vincent, et al.. A mini outburst from the nightside of comet 67P/Churyumov-Gerasimenko observed by the OSIRIS camera on Rosetta. Astronomy and Astrophysics - A&A, EDP Sciences, 2016, 596, A89 (10 p.). <10.1051/0004-6361/201527744>. <insu-01371309>

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