HR: 11:50h
AN: P51F-07    [PDF]
TI: Accretion of the Galilean Satellites
AU: * Canup, R M
EM: robin@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302
AU: Ward, W R
EM: ward@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut Street, Suite 400, Boulder, CO 80302
AB: We consider a scenario in which the Galilean satellites form within a circumplanetary accretion disk produced during the end stages of gas accretion onto Jupiter. In Canup and Ward (2002), we identified disk conditions compatible with three main constraints on satellite formation: 1) disk temperatures low enough for ices in the general region of Ganymede and Callisto, 2) satellite accretion times of $10^5$ years or more for consistency with an incompletely differentiated Callisto, and 3) satellite survival against inward orbital decay due to disk density wave torques. We found that such conditions can be simultaneously satisfied in a disk produced by a very slow inflow of gas and solids to Jupiter, with an implied rate of inflow during the satellite formation era of less than a Jovian mass per five million years. A similarly slow inflow rate is implied by the requirement that Jupiter had contracted to a radius smaller than the orbits of the Galilean satellites by the time of their formation (Magni and Coradini 2003). A slow inflow rate yields a much lower steady-state gas surface density than is implied by augmenting the mass of the current satellites to solar composition as has been done previously, and instead yields a "gas-starved" protosatellite disk. This implies that satellite accretion occurred in a relatively gas-free environment, and at a rate regulated by the inflow rather than by the local orbital period. Here we consider the ramifications of this gas-starved disk model for the accretional histories of the Galilean satellites, including implications for their individual growth times, and impact and migration histories.
DE: 6218 Jovian satellites
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting