The thermal, mechanical, structural, and dielectric properties of cometary nuclei after Rosetta. (arXiv:1905.01156v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Groussin_O/0/1/0/all/0/1">O. Groussin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Attree_N/0/1/0/all/0/1">N. Attree</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brouet_Y/0/1/0/all/0/1">Y. Brouet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ciarletti_V/0/1/0/all/0/1">V. Ciarletti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Davidsson_B/0/1/0/all/0/1">B. Davidsson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Filacchione_G/0/1/0/all/0/1">G. Filacchione</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fischer_H/0/1/0/all/0/1">H. H. Fischer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gundlach_B/0/1/0/all/0/1">B. Gundlach</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Knapmeyer_M/0/1/0/all/0/1">M. Knapmeyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Knollenberg_J/0/1/0/all/0/1">J. Knollenberg</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kokotanekova_R/0/1/0/all/0/1">R. Kokotanekova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuhrt_E/0/1/0/all/0/1">E. K&#xfc;hrt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leyrat_C/0/1/0/all/0/1">C. Leyrat</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marshall_D/0/1/0/all/0/1">D. Marshall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pelivan_I/0/1/0/all/0/1">I. Pelivan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Skorov_Y/0/1/0/all/0/1">Y. Skorov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Snodgrass_C/0/1/0/all/0/1">C. Snodgrass</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spohn_T/0/1/0/all/0/1">T. Spohn</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tosi_F/0/1/0/all/0/1">F. Tosi</a>

The physical properties of cometary nuclei observed today relate to their
complex history and help to constrain their formation and evolution. In this
article, we review some of the main physical properties of cometary nuclei and
focus in particular on the thermal, mechanical, structural and dielectric
properties, emphasizing the progress made during the Rosetta mission. Comets
have a low density of 480 $pm$ 220 kg m-3 and a low permittivity of 1.9 – 2.0,
consistent with a high porosity of 70 – 80 %, are weak with a very low global
tensile strength $<$100 Pa, and have a low bulk thermal inertia of 0 - 60 J K-1 m-2 s-1/2 that allowed them to preserve highly volatiles species (e.g. CO, CO2, CH4, N2) into their interior since their formation. As revealed by 67P/Churyumov-Gerasimenko, the above physical properties vary across the nucleus, spatially at its surface but also with depth. The broad picture is that the bulk of the nucleus consists of a weakly bonded, rather homogeneous material that preserved primordial properties under a thin shell of processed material, and possibly covered by a granular material; this cover might in places reach a thickness of several meters. The properties of the top layer (the first meter) are not representative of that of the bulk nucleus. More globally, strong nucleus heterogeneities at a scale of a few meters are ruled out on 67P small lobe.

The physical properties of cometary nuclei observed today relate to their
complex history and help to constrain their formation and evolution. In this
article, we review some of the main physical properties of cometary nuclei and
focus in particular on the thermal, mechanical, structural and dielectric
properties, emphasizing the progress made during the Rosetta mission. Comets
have a low density of 480 $pm$ 220 kg m-3 and a low permittivity of 1.9 – 2.0,
consistent with a high porosity of 70 – 80 %, are weak with a very low global
tensile strength $<$100 Pa, and have a low bulk thermal inertia of 0 – 60 J K-1
m-2 s-1/2 that allowed them to preserve highly volatiles species (e.g. CO, CO2,
CH4, N2) into their interior since their formation. As revealed by
67P/Churyumov-Gerasimenko, the above physical properties vary across the
nucleus, spatially at its surface but also with depth. The broad picture is
that the bulk of the nucleus consists of a weakly bonded, rather homogeneous
material that preserved primordial properties under a thin shell of processed
material, and possibly covered by a granular material; this cover might in
places reach a thickness of several meters. The properties of the top layer
(the first meter) are not representative of that of the bulk nucleus. More
globally, strong nucleus heterogeneities at a scale of a few meters are ruled
out on 67P small lobe.

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