Two Classes of Hot Jupiters

TL;DR

The paper classifies hot Jupiters into two categories based on temperature and Safronov number, exploring potential causes like migration halts and evaporation effects, including Helium loss impacting planetary radii.

Contribution

It introduces a new classification of hot Jupiters and discusses possible physical mechanisms behind their dichotomy, such as migration stopping points and atmospheric evaporation effects.

Findings

Identification of two distinct classes of hot Jupiters

Possible link between evaporation and planetary radius anomalies

Implication of migration and evaporation in planetary evolution

Abstract

We identify two classes of transiting planet, based on their equilibrium temperatures and Safronov numbers. We examine various possible explanations for the dichotomy. It may reflect the influence of planet or planetesimal scattering in determining when planetary migration stops. Another possibility is that some planets lose more mass to evaporation than others. If this evaporation process preferentially removes Helium from the planet, the consequent reduction in the mean molecular weight may explain why some planets have anomalously large radii.