Occurrence and Architecture of Kepler Planetary Systems as Functions of Stellar Mass and Effective Temperature

Abstract

The Kepler mission has discovered thousands of exoplanets around various stars with different spectral types (M, K, G, and F) and thus different masses and effective temperatures. Previous studies have shown that the planet occurrence rate, in terms of the average number of planets per star, drops with increasing stellar effective temperature ( T eff ). In this paper, with the final Kepler Data Release (DR25) catalog, we revisit the relation between stellar effective temperature (as well as mass) and planet occurrence, but in terms of the fraction of stars with planets and the number of planets per planetary system (i.e., planet multiplicity). We find that both the fraction of stars with planets and planet multiplicity decrease with increasing stellar temperature and mass. Specifically, about 75% late-type stars ( T eff  < 5000 K) have Kepler -like planets with an average planet multiplicity of ∼2.8, while for early-type stars ( T eff  > 6500 K) this fraction and the average multiplicity fall down to ∼35% and ∼1.8, respectively. The decreasing trend in the fraction of stars with planets is very significant with ΔAIC > 30, though the trend in planet multiplicity is somewhat tentative with ΔAIC ∼ 5. Our results also allow us to derive the dispersion of planetary orbital inclinations in relationship with stellar effective temperature. Interestingly, it is found to be similar to the well-known trend between obliquity and stellar temperature, indicating that the two trends might have a common origin.