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    Thermophysics of fractures on comet 67P/Churyumov-Gerasimenko

    Höfner, S. and Vincent, J.-B. and Blum, J. and Davidsson, B.J.R. and Sierks, H. and El-Maarry, Mohamed Ramy and Deller, J. and Hofmann, M. and Hu, X. and Pajola, M. and Barbieri, C. and Lamy, P.L. and Rodrigo, R. and Koschny, D. and Rickman, H. and Keller, H.U. and A’Hearn, M.F. and Auger, A.-T. and Barucci, M.A. and Bertaux, J.-L. and Bertini, I. and Bodewits, D. and Cremonese, G. and Da Deppo, V. and Debei, S. and De Cecco, M. and Fornasier, S. and Fulle, M. and Gicquel, A. and Groussin, O. and Gutiérrez, P.J. and Gutiérrez-Marqués, P. and Güttler, C. and Hviid, S.F. and Ip, W.-H. and Jorda, L. and Knollenberg, J. and Kovacs, G. and Kramm, J.-R. and Kührt, E. and Küppers, M. and La Forgia, F. and Lazzarin, M. and Lopez-Moreno, J.J. and Marzari, F. and Michalik, H. and Moissl-Fraund, R. and Moreno, F. and Mottola, S. and Naletto, G. and Oklay, N. and Preusker, F. and Scholten, F. and Shi, X. and Thomas, N. and Toth, I. and Tubiana, C. and Zitzmann, S. (2017) Thermophysics of fractures on comet 67P/Churyumov-Gerasimenko. Astronomy & Astrophysics 608 , A121. ISSN 0004-6361.

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    Abstract

    Context. The camera OSIRIS on board Rosetta obtained high-resolution images of the nucleus of comet 67P/Churyumov-Gerasimenko (67P). Great parts of the nucleus surface are composed of fractured terrain. Aims. Fracture formation, evolution, and their potential relationship to physical processes that drive activity are not yet fully understood. Observed temperatures and gas production rates can be explained or interpreted with the presence of fractures by applying appropriate modelling methods. Methods. We followed a transient thermophysical model approach that includes radiative, conductive, and water-ice sublimation fluxes by considering a variety of heliocentric distances, illumination conditions, and thermophysical properties for a set of characteristic fracture geometries on the nucleus of 67P. We computed diurnal temperatures, heat fluxes, and outgassing behaviour in order to derive and distinguish the influence of the mentioned parameters on fractured terrain. Results. Our analysis confirms that fractures, as already indicated by former studies about concavities, deviate from flat-terrain topographies with equivalent properties, mostly through the effect of self-heating. Compared to flat terrain, illuminated cometary fractures are generally warmer, with smaller diurnal temperature fluctuations. Maximum sublimation rates reach higher peaks, and dust mantle quenching effects on sublimation rates are weaker. Consequently, the rough structure of the fractured terrain leads to significantly higher inferred surface thermal inertia values than for flat areas with identical physical properties, which might explain the range of measured thermal inertia on 67P. Conclusions. At 3.5 AU heliocentric distance, sublimation heat sinks in fractures converge to maximum values >50 W / m2 and trigger dust activity that can be related mainly to H2O. Fractures are likely to grow through the erosive interplay of alternating sublimation and thermal fatigue. Key words:

    Metadata

    Item Type: Article
    Keyword(s) / Subject(s): comets: general, comets: individual, 67P/Churyumov-Gerasimenko, radiation mechanisms: thermal
    School: Birkbeck Schools and Departments > School of Science > Earth and Planetary Sciences
    Depositing User: Administrator
    Date Deposited: 17 Oct 2018 15:44
    Last Modified: 17 Oct 2018 15:44
    URI: http://eprints.bbk.ac.uk/id/eprint/24731

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