The effects of transport processes on the bulk composition of the first generation of planetesimals interior to the water iceline

Abstract

The CHNOS elemental budgets of rocky planets are crucial for their structure, evolution and potential chemical habitability. It is unclear how the nonlocal disk processes affecting dust in planet-forming disks affect the CHNOS elemental budgets of nascent planets both inside and outside the Solar System. We aim to quantify the coupled effect of dynamical and collisional processes on the initial refractory CHNOS budgets of planetesimals, forming interior to the water ice line for a Solar and non-Solar composition consistent with the star HIP 43393. Methods. We utilize the SHAMPOO code to track the effects of dynamical and collisional processes on 16000 individual dust monomers. Each monomer is here assigned a refractory chemical composition and mineralogy informed by the equilibrium condensation code GGCHEM given the P-T conditions at the initial position of the monomer. Monomers travel embedded in aggregates through a young class I disk, whose structure is calculated with the ProDiMo code. Furthermore, monomers are allowed to undergo dehydration and desulfurization. We find that solid material becomes well-mixed both radially and vertically. For both the Solar and HIP43393 compositions, the solid phase in the disk midplane regions interior to r~0.7AU can become enriched in hydrogen and sulfur by up to 10at% relative to predictions from purely local calculations. This originates from the inward radial transport of hydrated and sulfur-bearing minerals such as lizardite and iron sulfide. Nonlocal disk processing in a young turbulent, massive disk can lead to significant compositional homogenization of the midplane dust and by extension of the initial composition of planetesimals. Planetesimals forming at r<0.7AU may become enriched in hydrated minerals and sulfur, which could result in more widespread aqueous alteration interior to the water iceline compared to planetesimals that emerge...