Stellar Parameters and Metallicities of Stars Hosting Jovian and Neptunian Mass Planets: A Possible Dependence of Planetary Mass on Metallicity

TL;DR

This study investigates the relationship between stellar metallicity and the mass of orbiting planets, finding that stars with more massive planets tend to be more metal-rich, suggesting metallicity influences planetary mass formation.

Contribution

It provides a homogeneous analysis of stellar parameters for a large sample of planet-hosting stars and explores the potential link between metallicity and planetary mass.

Findings

Stars with Jovian planets are more metal-rich by ~0.15 dex.

Stars hosting only Neptunian planets tend to be more metal-poor.

Indicates a possible link between metallicity and maximum planetary mass.

Abstract

The metal content of planet hosting stars is an important ingredient which may affect the formation and evolution of planetary systems. Accurate stellar abundances require the determinations of reliable physical parameters, namely the effective temperature, surface gravity, microturbulent velocity, and metallicity. This work presents the homogeneous derivation of such parameters for a large sample of stars hosting planets (N=117), as well as a control sample of disk stars not known to harbor giant, closely orbiting planets (N=145). Stellar parameters and iron abundances are derived from an automated analysis technique developed for this work. As previously found in the literature, the results in this study indicate that the metallicity distribution of planet hosting stars is more metal-rich by ~0.15 dex when compared to the control sample stars. A segregation of the sample according to planet mass indicates that the metallicity distribution of stars hosting only Neptunian-mass planets (with no Jovian-mass planets) tends to be more metal-poor in comparison with that obtained for stars hosting a closely orbiting Jovian planet. The significance of this difference in metallicity arises from a homogeneous analysis of samples of FGK dwarfs which do not include the cooler and more problematic M dwarfs. This result would indicate that there is a possible link between planet mass and metallicity such that metallicity plays a role in setting the mass of the most massive planet. Further confirmation, however, must await larger samples.