Revealing a universal planet-metallicity correlation for planets of different solar-type stars

Abstract

The metallicity of exoplanet systems serves as a critical diagnostic of planet formation mechanisms. Previous studies have demonstrated the planet-metallicity correlation for large planets (RP ≥ 4 RE); however, a correlation has not been found for smaller planets. With a sample of 406 Kepler objects of interest whose stellar properties are determined spectroscopically, we reveal a universal planetmetallicity correlation: not only gas-giant planets (3.9 RE