The late accretion and erosion of Vesta’s crust recorded by eucrites and diogenites as an astrochemical window into the formation of Jupiter and the early evolution of the Solar System

Abstract

The circumsolar disc was the birthplace of both planetesimals and giant planets, yet the details of their formation histories are as elusive as they are important to understand the origins of the Solar System. For decades the limited thickness of Vesta’s basaltic crust, revealed by the link between the asteroid and the howardite-eucrite-diogenite family of meteorites, and its survival to collisional erosion offered an important constraint for the study of these processes. Some results of the Dawn mission, however, cast doubts on our understanding of Vesta’s interior composition and of the characteristics of its basaltic crust, weakening this classical constraint. In this work we investigate the late accretion and erosion experienced by Vesta’s crust after its differentiation and recorded in the composition of eucrites and diogenites and show that it offers an astrochemical window into the earliest evolution of the Solar System. In our proof-of-concept case study focusing on the late accretion and erosion of Vesta’s crust during the growth and migration of Jupiter, the water enrichment of eucrites appears to be a sensitive function of Jupiter’s migration while the enrichment in highly-siderophile elements of diogenites appears to be particularly sensitive to the size-frequency distribution of the planetesimals. The picture depicted by the enrichments created by late accretion in eucrites and diogenites is not qualitatively affected by the uncertainty on the primordial mass of Vesta. Crustal erosion, instead, is more significantly affected by said uncertainty and Vesta’s crust survival appears to be mainly useful to study violent collisional scenarios where highly energetic impacts can strip significant amounts of vestan material while limitedly contributing to Vesta’s late accretion. While our proof-of-concept case study is based on a simplified physical model and explores only a limited set of scenarios, our results suggest that the astrochemical record of the late accretion and erosion of Vesta’s crust provided by eucrites and diogenites can be used as a tool to investigate any process or scenario associated to the evolution of primordial Vesta and of the early Solar System.