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Paper: astro-ph/0510798

Date: Fri, 28 Oct 2005 10:23:28 GMT (316kb)

Title: Modeling the Jovian subnebula: II - Composition of regular satellites
ices

Authors: Olivier Mousis and Yann Alibert

Comments: 9 pages, A&A, in press
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We use the evolutionary turbulent model of Jupiter's subnebula described by
Alibert et al. (2005a) to constrain the composition of ices incorporated in its
regular icy satellites. We consider CO2, CO, CH4, N2, NH3, H2S, Ar, Kr, and Xe
as the major volatile species existing in the gas-phase of the solar nebula.
All these volatile species, except CO2 which crystallized as a pure condensate,
are assumed to be trapped by H2O to form hydrates or clathrate hydrates in the
solar nebula. Once condensed, these ices were incorporated into the growing
planetesimals produced in the feeding zone of proto-Jupiter. Some of these
solids then flowed from the solar nebula to the subnebula, and may have been
accreted by the forming Jovian regular satellites. We show that ices embedded
in solids entering at early epochs into the Jovian subdisk were all vaporized.
This leads us to consider two different scenarios of regular icy satellites
formation in order to estimate the composition of the ices they contain. In the
first scenario, icy satellites were accreted from planetesimals that have been
produced in Jupiter's feeding zone without further vaporization, whereas, in
the second scenario, icy satellites were accreted from planetesimals produced
in the Jovian subnebula. In this latter case, we study the evolution of carbon
and nitrogen gas-phase chemistries in the Jovian subnebula and we show that the
conversions of N2 to NH3, of CO to CO2, and of CO to CH4 were all inhibited in
the major part of the subdisk. Finally, we assess the mass abundances of the
major volatile species with respect to H2O in the interiors of the Jovian
regular icy satellites. Our results are then compatible with the detection of
CO2 on the surfaces of Callisto and Ganymede and with the presence of NH3
envisaged in subsurface oceans within Ganymede and Callisto.

\\ ( http://arXiv.org/abs/astro-ph/0510798 , 316kb)