1111.0768 (Yuri Skorov et al.)
Yuri Skorov, Jürgen Blum
We developed a thermophysical model for cometary nuclei, which is based upon
the assumption that comets form by the gravitational instability of an ensemble
of dust and ice aggregates. Under this condition, the tensile strength of the
ice-free outer layers of a cometary nucleus can be calculated, using the
dust-aggregate collision and adhesion model of Weidling et al. (2011). Based on
available laboratory data on the gas permeability and thermal conductivity of
ice-free dust layers, we derived the temperature and pressure at the dust-ice
interface for pure water and pure carbon dioxide ice. Comparison of the vapor
pressure below the dust crust with its tensile strength allows the prediction
of dust release from cometary surfaces. Our model predicts dust activity for
pure CO2 ice and for heliocentric distances of <~ 3 AU, whereas pure H2O ice
cannot explain the dust emission
View original:
http://arxiv.org/abs/1111.0768
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