Modeling the thermodynamical conditions in the Uranian subnebula - Implications for regular satellite composition

Abstract

We study the thermodynamical conditions existing in the Uranian subnebula from which the regular satellites were presumably formed, assuming it was produced by an earth-sized body impact on proto-Uranus (Stevenson 1984; Slattery et al. 1992). Two evolutionary turbulent models of the Uranian subnebula are constructed. Both are derived from the solar nebula analytical model of Dubrulle (1993) and Drouart et al. (1999). Each model provides a distinct chemical composition which depends on the assumed origin of the subdisk's material (proto-Uranus or impactor ejected material). Moreover, the evolution of the chemistry of C and N compounds is examined in order to assess the nature of major volatiles trapped into the ices of regular satellites. The temporal evolution of the D/H ratio in water is also explored in the Uranian subdisk, as a function of the gas phase composition. Such an analysis may provide constraints on the origin of the material which led to the formation of the regular satellite system.