Eccentricity Dependence on Iron Abundance

Abstract

The occurrence and eccentricity distribution of planets as a function of period is significantly different for iron-rich and iron-poor planet systems. We find that iron-poor stars with planets having periods between 525 and 600 days have higher eccentricity than such systems outside this range. If whole planet pollution causes the correlation of giant planet eccentricity with stellar iron abundance, then this cluster could be due to a paucity of pollution in this period range. Newly reported patterns of planet occurrence must result from planet system architectural features such as the snow line, followed by subsequent migration. Different results favor pollution or higher initial iron abundance causing the higher occurrence fraction of giant planets hosted by iron-rich stars, but the two explanations could be complementary. Relations between planet and stellar parameters are a major product of planet-finding, which promise further insights into star-planet system formation and evolution. Collaborators are sought to study these patterns. We expect a spirited debate over the relative contributions of initial abundances, disk accretion, and whole planet accretion.