Condensation of Rocky Material in Astrophysical Environments

TL;DR

This paper explores how volatility-driven fractionation influences the formation of early solids in protoplanetary disks, using equilibrium condensation calculations to predict mineral compositions under various conditions.

Contribution

It provides a comprehensive graphical survey of condensation results for different bulk compositions, highlighting the role of disequilibrium effects in meteoritic component formation.

Findings

Equilibrium condensation models predict mineral phases in early solar system solids.

Disequilibrium effects were common, especially in less refractory meteoritic components.

Hierarchical accretion and vapor-solid cycling influenced meteoritic mineral formation.

Abstract

Volatility-dependent fractionation of the rock-forming elements at high temperatures is an early, widespread process during formation of the earliest solids in protoplanetary disks. Equilibrium condensation calculations allow prediction of the identities and compositions of mineral and liquid phases coexisting with gas under presumed bulk chemical, pressure and temperature conditions. A graphical survey of such results is presented for systems of solar and non-solar bulk composition. Chemical equilibrium was approached to varying degrees in the local regions where meteoritic chondrules, Ca-Al-rich inclusions, matrix and other components formed. Early, repeated vapor-solid cycling and homogenization, followed by hierarchical accretion in dust-rich regions, is hypothesized for meteoritic inclusions. Disequilibrium chemical effects appear to have been common at all temperatures, but increasingly so in less refractory meteoritic components. Work is needed to better model high-temperature solid solutions, indicators of these processes.