Paper: astro-ph/0601043

Date: Tue, 3 Jan 2006 12:34:14 GMT (63kb)

Title: Jupiter's composition: sign of a (relatively) late formation in a
chemically evolved protosolar disk

Authors: Tristan Guillot (OCA), Ricardo Hueso

Comments: 6 pages, 3 figures, in press in MNRAS. The definitive version is
available at www.blackwellsynergy.com

Proxy: ccsd ccsd-00016408
\\
It has been proposed that the enrichment in noble gases found by Galileo in
Jupiter's atmosphere can be explained by their delivery inside cold
planetesimals. We propose instead that this is a sign that the planet formed in
a chemically evolved disk and that noble gases were acquired mostly in gaseous
form during the planet's envelope capture phase. We show that the combined
settling of grains to the disk midplane in the cold outer layers, the
condensation of noble gases onto these grains at temperatures below 20-30K, and
the evaporation from high disk altitudes effectively lead to a progressive,
moderate enrichment of the disk. The fact that noble gases are vaporized from
the grains in the hot inner disk regions (e.g. Jupiter formation region) is not
a concern because a negative temperature gradient prevents convection from
carrying the species into the evaporating region. We show that the ~2 times
solar enrichment of Ar, Kr, Xe in Jupiter is hence naturally explained by a
continuous growth of the planet governed by viscous diffusion in the protosolar
disk in conjunction with an evaporation of the disk and its progressive
enrichment on a million years timescale.

\\ ( http://arXiv.org/abs/astro-ph/0601043 , 63kb)