Was Earth's water acquired locally during the earliest phases of the Solar System formation?

TL;DR

This study uses quantum chemistry to model water adsorption on dust grains in the early Solar System, suggesting Earth's water could have been acquired locally rather than from distant sources.

Contribution

It introduces a Gaussian distribution of water binding energies to better model sublimation and water distribution in the protoplanetary disk, challenging the traditional snowline concept.

Findings

Model reproduces Earth's water abundance range

Matches hydration trends in chondrites

Supports local water acquisition hypothesis

Abstract

The origin of the terrestrial water remains debated, as standard Solar System formation models suggest that Earth formed from dry grains, inside the snowline of the Proto-Solar Nebula (PSN). Here, we revisit this issue through the lens of computational chemistry. While the classically used snowline relies on a single condensation temperature, recent work in quantum chemistry shows that the binding energy of water on icy grains has a gaussian distribution, which implies a gradual sublimation of water rather than a sharp transition. We use the computed distribution of binding energies to estimate the radial distribution of adsorbed ice on the dust grains across the PSN protoplanetary disk. Our model reproduces the full range of estimated water abundances on Earth and matches the hydration trends observed in chondrite groups at their predicted formation distances. Thus, we suggest that a significant fraction of Earth's water may have been acquired locally at early stages of the Solar System formation, without requiring delivery from beyond the classical snowline.