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Catalogue POP – Notice individuelle de publication

Höfner Sebastian, Vincent Jean-Baptiste, Blum J., Davidsson Björn, Sierks Holger, El-Maarry Mohamed Ramy, Deller Jakob, Hofmann M., Hu X., Pajola Maurizio, Barbieri Cesare, Lamy Philippe, Rodrigo Rafael, Koschny Detlef, Rickman Hans, Keller Horst Uwe, A'Hearn M. F., Auger Anne-Thérèse, Barucci Maria Antonella, Bertaux Jean-Loup, Bertini Ivano, Bodewits Dennis, Cremonese Gabriele, Da Deppo Vania, Debei Stefano, De Cecco M., Fornasier Sonia, Fulle Marco, Gicquel Adeline, Groussin Olivier, Gutierrez Pedro J., Gutiérrez-Marques P., Güttler Carsten, Hviid Stubbe F., Ip W., Jorda Laurent, Knollenberg Jörg, Kovacs Gabor, Kramm Rainer, Kührt Ekkehard, Küppers Michael, La Forgia Fiorangela, Lazzarin Monica, López-Moreno José J., Marzari Francesco, Michalik Harald, Moissl-Fraund R., Moreno Fernando, Mottola Stefano, Naletto Giampiero, Oklay Nilda, Preusker Frank, Scholten Frank, Shi X., Thomas Nicholas, Toth Imre, Tubiana Cecilia, Zitzmann S.

Thermophysics of fractures on comet 67P/Churyumov-Gerasimenko

Astronomy and Astrophysics, 2017, vol. 608

Référence DOI : 10.1051/0004-6361/201628726
Référence ADS : 2017A&A...608A.121H

Résumé :

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. <BR /> 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. <BR /> 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. <BR /> 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. <BR /> Conclusions: At 3.5 AU heliocentric distance, sublimation heat sinks in fractures converge to maximum values >50 W / m<SUP>2</SUP> and trigger dust activity that can be related mainly to H<SUB>2</SUB>O. Fractures are likely to grow through the erosive interplay of alternating sublimation and thermal fatigue.

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