Gas dissipation from the protosatellite disk of Jupiter

We consider the dissipation of the gaseous component from the gas-dust accretion disk of Jupiter in which the Galilean satellites were formed. The thermal dissipation of hydrogen and helium is shown to be ineffective. It could ensure the loss of gas only for a low-mass disk and only if the rarefied outer layers of the disk are heated to 10(4) K. Such a high disk temperature is not reached through Jupiter's radiation in existing models of its formation, but it could be provided by UV radiation of the early Sun after the dissipation of the protoplanetary disk. The viscous dissipation (with a viscosity parameter a alpha greater than or equal to 10(-3) in the alpha-disk model) related to disk accretion onto Jupiter could disperse a low-mass disk in less than or equal to10(7) years. A magnetocentrifugal mechanism, which produced a disk wind during accretion capable of carrying away similar to0.1 of the accreted gas mass, was probably also involved in the dispersal of the Jovian disk. Differential dispersion, with the loss of only hydrogen and helium and the retention of water vapor and heavier gases in the disk, is possible only in a low-mass disk model. We conclude that the water contained in the Galilean satellites was brought in mainly by solid planetesimals captured into the disk during mutual inelastic collisions in Jupiter's sphere of influence.