The Gaia spectroscopic catalogue of exoplanets and host stars

TL;DR

This paper presents a comprehensive, homogeneous, and precise Gaia-based catalogue of exoplanet host stars and their planets, enabling improved parameter estimation and insights into planetary diversity and Galactic population characteristics.

Contribution

It provides the first Gaia-based homogeneous parameterization of 2573 exoplanet host stars and their planets, with improved precision and new insights into their Galactic and chemical properties.

Findings

Stellar radii are derived with less than 3% uncertainty.

A correlation between host star metallicity and planet size/mass is observed.

A potential bimodality in giant planet properties related to Galactic location is suggested.

Abstract

Complete, accurate, and precise catalogues of exoplanet host star (EHS) properties are essential to deriving high-quality exoplanet parameters. This paper aims at homogeneously parameterising EHS and their exoplanets, using Gaia and GSP-spec data. For 2573 EHS, we computed their L*, R*, and M*, with no prior assumption from stellar evolution models. Their Galactic positions, kinematic and orbital properties were derived. We re-scaled Mp and Rp of 3556 exoplanets, fully consistently with the stellar data. These new stellar Teff, L*, and R* are in rather good agreement with literature values but are more precise. In particular, R* are derived with typically less than 3% uncertainty; this reduces the uncertainty on Rp significantly and allows for a finer analysis of the decrease in the number of planets around the evaporation valley. Larger differences, however, were found for M*. We note that the EHS population is rather diverse in terms of the chemical and Galactic properties, although they are all found in the Solar vicinity, close to the Local spiral arm. Most EHS belong to the thin disc, but some older thick disc and halo members have also been identified. For the less massive planets, the average Rp increases with the metallicity of the host star. For giant planets, a dichotomy between dense and inflated planets is found. Denser planets tend to be more massive as the metallicity of the host star increases, while inflated planets are more massive for less metallic hosts. If confirmed, this bimodality implies that the diversity of giant exoplanets depends on their Galactic birth locus, with dense giant planets being more numerous than inflated ones when [M/H]>~1.5 times Solar, as in the central Milky Way regions. The Gaia spectroscopic catalogue of exoplanets and their host stars is large, homogeneous, and precise. It would be a useful added-value for planetary studies.