Planet occurrence and stellar metallicity for KOIs

Using a sample of over 20000 Kepler stars with spectroscopic metallicities from the LAMOST survey, we explore how the exoplanet population depends on host star metallicity as a function of orbital period and planet size. We find that exoplanets with orbital periods less than 10 days are preferentially found around metal-rich stars ([Fe/H]{simeq}0.15+/-0.05dex).

The occurrence rates of these hot exoplanets increases to ~30% for super-solar metallicity stars from ~10% for stars with a sub-solar metallicity. Cooler exoplanets, which reside at longer orbital periods and constitute the bulk of the exoplanet population with an occurrence rate of >~90%, have host star metallicities consistent with solar. At short orbital periods, P<10days, the difference in host star metallicity is largest for hot rocky planets (<1.7R_{Earth}_), where the metallicity difference is [Fe/H]{simeq}0.25+/-0.07dex.