Thermal Processing of Solids Encountering a Young Jovian Core

TL;DR

This study investigates how the thermal state of Jupiter's core during formation affects volatile retention, suggesting that Jupiter's nitrogen enrichment implies a formation location beyond the N2 snowline or alternative nitrogen preservation mechanisms.

Contribution

It introduces a model linking core temperature during formation to volatile retention, providing new insights into Jupiter's formation environment and nitrogen enrichment.

Findings

Hot cores drive off volatiles before accretion.

Cool cores can inherit volatile-rich solids.

Jupiter's formation likely occurred beyond the N2 snowline or involved nitrogen preservation.

Abstract

Jupiter's enhancement in nitrogen relative to hydrogen when compared to the Sun has been interpreted as evidence that its early formation occurred beyond the N$_{2}$ snowline ($\sim$ 20-40 AU). However, the rapid growth necessary to form Jupiter before the dissipation of the solar nebula would lead to the forming planet's core reaching very high temperatures ($>$1000 K), which would lead to it warming its surroundings. Here, we explore the effects of a luminous planetary core on the solids that it ultimately accretes. We find that a critical transition occurs where very hot (rapidly accreting) cores drive off volatiles prior to accretion, while cool cores (slowly accreting) are able to inherit volatile rich solids. Given Jupiter's nitrogen enrichment, if it formed beyond the N$_{2}$ snowline, its core could not have accreted solids at a rate above 10$^{-10}$ M$_{\odot}$ yr$^{-1}$. Our results suggest that either Jupiter formed in more distal regions of the solar nebula, or nitrogen loss was suppressed, either by its incorporation in more refractory carriers or because it was trapped within ices which devolatilized at higher temperatures.