The ancient heritage of water ice in the solar system

TL;DR

This paper investigates the origins of water in the solar system, concluding that interstellar ices, rather than disk chemistry, are the primary source of Earth's water, with implications for planetary system formation.

Contribution

It demonstrates that ion-driven chemistry in protoplanetary disks is insufficient to produce observed deuterium enrichments, highlighting interstellar ices as the main water source.

Findings

Ion-driven pathways are inefficient for deuterated water formation.

Interstellar ices are likely the primary source of solar system water.

Implications for water availability in other planetary systems.

Abstract

Identifying the source of Earth's water is central to understanding the origins of life-fostering environments and to assessing the prevalence of such environments in space. Water throughout the solar system exhibits deuterium-to-hydrogen enrichments, a fossil relic of low-temperature, ion-derived chemistry within either (i) the parent molecular cloud or (ii) the solar nebula protoplanetary disk. Utilizing a comprehensive treatment of disk ionization, we find that ion-driven deuterium pathways are inefficient, curtailing the disk's deuterated water formation and its viability as the sole source for the solar system's water. This finding implies that if the solar system's formation was typical, abundant interstellar ices are available to all nascent planetary systems.