No correlation between the Transit-Depth Metallicity of Kepler gas giant confirmed and candidates planets: A Bayesian Approach

Abstract

Previous attempts to study the correlation between the transit depth and the stellar metallicity of Kepler gas giant planets has led to different results. A weakly significant negative correlation was reported from the Kepler's (Q1-Q12) gas giant candidates with estimated radii of 5-20R$_\odot$ and [Fe/H] values taken from the Kepler Input Catalog (KIC). With the release of the last Kepler catalog (Q1-Q17), we now have the largest homogeneous sample of exoplanets. This enables a solid statistical analysis of this correlation. In the present work, we revise this correlation, within a Bayesian framework, for two large homogeneous samples: confirmed and complete. We expand a Hierarchical model to account for false positives in the studied samples. Our statistical analysis reveals no correlation between the transit depth and the stellar metallicity. The fact that we found no evidence of such correlation will have implications for planet formation theory and interior structure of giant planets.