MASS TRANSPORT AROUND COMETS AND ITS IMPACT ON THE SEASONAL DIFFERENCES IN WATER PRODUCTION RATES

作者：Rubin M^*; Fougere N; Altwegg K; Combi M R; Le Roy L; Tenishev V M; Thomas N

来源：Astrophysical Journal, 2014, 788(2): 168.

DOI：10.1088/0004-637X/788/2/168

• comets: general
• comets: individual (67P/Churyumov-Gerasimenko)
• methods: numerical

Comets are surrounded by a thin expanding atmosphere, and although the nucleus' gravity is small, some molecules and grains, possibly with the inclusion of ices, can get transported around the nucleus through scattering (atoms/molecules) and gravitational pull (grains). Based on the obliquity of the comet, it is also possible that volatile material and icy grains get trapped in regions, which are in shadow until the comet passes its equinox. When the Sun rises above the horizon and the surface starts to heat up, this condensed material starts to desorb and icy grains will sublimate off the surface, possibly increasing the comet's neutral gas production rate on the outbound path. In this paper we investigate the mass transport around the nucleus, and based on a simplified model, we derive the possible contribution to the asymmetry in the seasonal gas production rate that could arise from trapped material released from cold areas once they come into sunlight. We conclude that the total amount of volatiles retained by this effect can only contribute up to a few percent of the asymmetry observed in some comets.

• 出版日期2014-6-20