On the light-absorbing surface layer of cometary nuclei: II. Thermal modeling
2002 (English)In: Icarus, ISSN 0019-1035, Vol. 159, no 1, 239-258 p.Article in journal (Refereed) Published
The classical way to treat absorption of solar light in thermophysical modelling of cometary nuclei (and other ice-rich bodies such as jovian satellites), has been to assume complete opaqueness of the surface material. However, as shown by Davidsson and Skorov (2002), substantial light penetration can occur in porous ice even if it is very dusty, implying that gradual absorption of energy in a surface layer should be accounted for.
We present a thorough comparison between a surface energy absorption model and a layer energy absorption model, for various combinations of heliocentric distances, conductivities, opacities, pore sizes and rotational periods relevant for cometary nuclei, by fully solving the coupled differential equations of heat transfer and gas diffusion. We find substantial differences between the models in terms of gas production rate, thermal lag angle, surface temperature, and the origin of coma molecules. For example, the surface energy absorption model overestimates the total gas production by a factor 2-7, underestimates the lag angle by a factor 2-3, and places the origin of coma molecules at the surface, instead of the near--surface interior.
Place, publisher, year, edition, pages
2002. Vol. 159, no 1, 239-258 p.
surfaces, comets, thermal histories
Astronomy, Astrophysics and Cosmology
IdentifiersURN: urn:nbn:se:uu:diva-15044DOI: doi:10.1006/icar.2002.6912OAI: oai:DiVA.org:uu-15044DiVA: diva2:42815