37th DPS Meeting, 4-9 September 2005
Session 25 Planet and Satellite Formation
Oral, Tuesday, September 6, 2005, 2:00-3:50pm, Law LG19

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[25.09] Satellite accretion during inflow to gas giant planets

R. M. Canup, Wm. R. Ward (Southwest Research Institute)

We consider a scenario (after Canup and Ward 2002) in which the regular satellites of gas giants form within circumplanetary accretion disks produced during the final stages of gas accretion (e.g., Lubow et al. 1999; D'Angelo et al. 2002). For a given inflow rate of gas and solids, a quasi steady-state circumplanetary gas disk is produced through a balance of the inflow supply and the disk's internal viscous evolution, assuming that the disk viscous spreading time is short compared to the timescale over which the inflow changes. Once in orbit, accumulation of inflowing solids causes the total mass of disk solids to build-up over time, with satellites then forming at a rate regulated by the delivery of solids from heliocentric orbit. Canup and Ward (2002) proposed that such conditions provide a natural means to explain the density gradient of the Galilean satellites, satellite survival against Type I orbital decay, and Callisto's apparent state of partial differentiation (e.g., Anderson et al. 2001). Here we present simulations of satellite accretion within a disk to which solid material is continuously supplied and growing satellite embryos are subject to radial decay and loss due to interactions with an accompanying gas disk. We find that in such a system, the total satellite mass regulates itself about a value determined by the disk and inflow parameters. We discuss the implications of this for the Jovian and Saturnian satellite systems, which each contain ~O(10-4) times their respective planet's mass.

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Bulletin of the American Astronomical Society, 37 #3
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