Thermal Evolution and Core Formation on Asteroid 4 Vesta in the Magma Ocean Regime

Abstract

Geochemical observations of the eucrite and diogenite meteorites, together with observations made by NASAs Dawn spacecraft while orbiting asteroid 4 Vesta, indicate that Vesta has differentiated to form a crust, mantle, and core. Eucrite and diogenite petrology is best explained by solidification of the crust from a magma ocean constituting 60-70% of Vestas silicates [3], or a temperature of ~1550 C. The abundances of moderately siderophile elements (Ni, Co, Mo, W, and P) in eucrites require that essentially all of the metallic phase in Vesta segregated to form a core prior to eucrite formation and likely reached a temperature of 1450- 1575 C. These observations provide important constraints on Vestas thermal evolution. The high inferred temperature indicates that convective heat transport must have been important during part of Vestas thermal evolution. In this study, we model Vestas thermal evolution in the magma ocean regime