An Empirical Mass-Radius Relation for Cool Giant Planets

TL;DR

This paper establishes an empirical mass-radius relation specifically for cool giant planets above 15 Earth masses, improving radius estimates by accounting for temperature differences and using hierarchical Bayesian modeling.

Contribution

It introduces a new mass-radius relation for cool giant planets derived from hierarchical Bayesian analysis, distinguishing it from previous models that did not differentiate between hot and cool giants.

Findings

The relation is a quadratic function in log mass with a power-law dispersion.

Parametric uncertainties are quantified via MCMC.

Results align well with interior models and solar system giants.

Abstract

Probabilistic relationships between the mass and radius of planets are useful for a variety of purposes, including estimating the yields of planet discovery efforts and the radii of discovered planets given their masses. Previous work on giant planets often do not make the important distinction between cool and (inflated) hot giants. This can lead to needlessly large uncertainties and overestimated radii for the cooler objects. Using hierarchical bayesian modeling and the AIC model selection criterion, we identify an empirical mass-radius relationship for cool giant planets above 15 Earth masses. It takes the form of a quadratic function in log mass, with a power-law dispersion. Parametric uncertainties from MCMC are provided, and we compare our results with the outputs of interior structure models and the radii of the solar system giant planets, which fit comfortably within our relation.