Planetary Orbit Eccentricity Trends (POET). I. The Eccentricity–Metallicity Trend for Small Planets Revealed by the LAMOST–Gaia–Kepler Sample

Orbital eccentricity is one of the basic planetary properties, whose distribution may shed light on history planet formation and evolution. Here, in a series works Planetary Orbit Eccentricity Trends (dubbed POET), we study eccentricities their dependence stellar/planetary properties. In this paper, first work POET series, investigate whether how small planets depend stellar metallicities (e.g., [Fe/H]). Previous studies giant have found significant correlation between host metallicities. Nevertheless, such exists (e.g. super-Earth sub-Neptune) remains unclear. benefiting from large homogeneous LAMOST-Gaia-Kepler sample, characterize distributions 244 (286) single (multiple) transiting systems with transit duration ratio method. We confirm eccentricity-metallicity trend that increase Interestingly, similar metallicity also radial velocity (RV) sample. mutual inclination multiple increases metallicity, which predicts moderate rising trend. Our results (inclination) for support core accretion model formation, they could be footprints self (and/or external) excitation processes during