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    Sunset jets observed on comet 67P/Churyumov-Gerasimenko sustained by subsurface thermal lag

    Shi, X. and Hu, X. and Sierks, H. and Güttler, C. and A’Hearn, M. and Blum, J. and El-Maarry, Mohamed Ramy and Kührt, E. and Mottola, S. and Pajola, M. and Oklay, N. and Fornasier, S. and Tubiana, C. and Keller, H.U. and Vincent, J.-B. and Bodewits, D. and Höfner, S. and Lin, Z.-Y. and Gicquel, A. and Hofmann, M. and Barbieri, C. and Lamy, P.L. and Rodrigo, R. and Koschny, D. and Rickman, H. and Barucci, M.A. and Bertaux, J.-L. and Bertini, I. and Cremonese, G. and Da Deppo, V. and Davidsson, B. and Debei, S. and De Cecco, M. and Fulle, M. and Groussin, O. and Gutiérrez, P.J. and Hviid, S.F. and Ip, W.-H. and Jorda, L. and Knollenberg, J. and Kovacs, G. and Kramm, J.-R. and Küppers, M. and Lara, L.M. and Lazzarin, M. and Lopez-Moreno, J.J. and Marzari, F. and Naletto, G. and Thomas, N. (2016) Sunset jets observed on comet 67P/Churyumov-Gerasimenko sustained by subsurface thermal lag. Astronomy & Astrophysics 586 , A7. ISSN 0004-6361.

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    Abstract

    We present observations of sunset jets on comet 67P/Churyumov-Gerasimenko by Rosetta/OSIRIS camera. In late April 2015, when the comet was at a heliocentric distance of ~1.8 AU, clusters of dust jets that originated in the Ma’at region on the comet’s small lobe were identified from multipleimages and were apparently sustained for about an hour beyond local sunset. Emanating from the shadowed nucleus, these jets became visible by solar illumination at their apparent sources up to only a few tens of meters above the nucleus surface. We investigate the plausibility of these jets as having been triggered by water ice sublimation and sustained by thermal lag in the subsurface beyond sunset. A general thermo-physical model was parameterized such that the thermal lag in the subsurface is consistent with the elapsed time of observation after sunset. It is found that the sublimation of water ice from a depth of 6 mm and with a low thermal inertia of 50 W m-2 K-1 s1/2 could explain the spatial pattern and evolution of the apparent sources, particularly their disappearance due to the eventual cooling of the subsurface. Our analysis suggests that these sunset jets were essentially day-side dust activities that continued after sunset. Specific observational conditions for the sunset jets constrain their possible sources to mostly within the less abrupt, dusty terrains. The uneven distribution of these jets is possibly related to subsurface inhomogeneities in the dusty area.

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): comets: individual: 67P/Churyumov-Gerasimenko
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 09 Nov 2018 14:41
    Last Modified: 09 Nov 2018 14:41
    URI: http://eprints.bbk.ac.uk/id/eprint/25022

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