Thermal Evolution and Activity of Comet 9P/Tempel 1 and Simulation of a Deep Impact

ABSTRACT We use a quasi–three‐dimensional thermal evolution model for a spherical comet nucleus that takes into account the diurnal and latitudinal variation of the solar flux but neglects lateral heat conduction. We model the thermal evolution and activity of comet 9P/Tempel 1, in anticipation of the Deep Impact mission encounter with the comet. We also investigate the possible outcome of a projectile impact, assuming that all the energy is absorbed as thermal energy. An interesting result of this investigation is that the estimated amount of dust ejected due to the impact is equivalent to 2–2.6 days of activity during “quiet” conditions at perihelion. We show that production rates of volatiles that are released in the interior of the nucleus depend strongly on the porous structure, in particular on the surface‐to‐volume ratio of the pores. We develop a more accurate model for calculating this parameter, based on a distribution of pore sizes, rather than on a single, average pore size.

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