How fast do Jupiters grow? Signatures of the snowline and growth rate in the distribution of gas giant planets

TL;DR

This paper provides observational and theoretical evidence that the snowline significantly influences gas giant planet formation, affecting their distribution, growth, and migration patterns, with implications for understanding planet population characteristics.

Contribution

It identifies a mass-semimajor axis boundary linked to the snowline and models gas accretion dynamics, offering new insights into planet formation processes.

Findings

Planets are often found beyond the snowline before inward migration.

Gas giants accrete approximately 70% of inward-flowing gas.

Inner disc holes in transition discs are consistent with ongoing gas accretion.

Abstract

We present here observational evidence that the snowline plays a significant role in the formation and evolution of gas giant planets. When considering the population of observed exoplanets, we find a boundary in mass-semimajor axis space that suggests planets are preferentially found beyond the snowline prior to undergoing gap-opening inward migration and associated gas accretion. This is consistent with theoretical models suggesting that sudden changes in opacity -- as would occur at the snowline -- can influence core migration. Furthermore, population synthesis modelling suggests that this boundary implies that gas giant planets accrete ~ 70 % of the inward flowing gas, allowing ~ 30$ % through to the inner disc. This is qualitatively consistent with observations of transition discs suggesting the presence of inner holes, despite there being ongoing gas accretion.