Constraints from deuterium on the formation of icy bodies in the Jovian system and beyond

TL;DR

This paper explores how deuterium ratios in water ice can reveal the formation environments of icy bodies in the Solar system, especially Jupiter's satellites, using models of hot and cold subnebulae and upcoming telescope data.

Contribution

It introduces a detailed analysis of deuterium-to-hydrogen ratios as markers for formation conditions of icy bodies, comparing hot and cold subnebula models and their implications.

Findings

Hot subnebula model predicts near-Solar D:H ratios in satellites.

Cold subnebula model predicts over-Solar D:H ratios in satellites.

Future observations will help distinguish formation scenarios.

Abstract

We consider the role of deuterium as a potential marker of location and ambient conditions during the formation of small bodies in our Solar system. We concentrate in particular on the formation of the regular icy satellites of Jupiter and the other giant planets, but include a discussion of the implications for the Trojan asteroids and the irregular satellites. We examine in detail the formation of regular planetary satellites within the paradigm of a circum-Jovian subnebula. Particular attention is paid to the two extreme potential subnebulae - "hot" and "cold". In particular, we show that, for the case of the "hot" subnebula model, the D:H ratio in water ice measured from the regular satellites would be expected to be near-Solar. In contrast, satellites which formed in a "cold" subnebula would be expected to display a D:H ratio that is distinctly over-Solar. We then compare the results obtained with the enrichment regimes which could be expected for other families of icy small bodies in the outer Solar system - the Trojan asteroids and the irregular satellites. In doing so, we demonstrate how measurements by Laplace, the James Webb Space Telescope, HERSCHEL and ALMA will play an important role in determining the true formation locations and mechanisms of these objects.