Planetary Orbit Eccentricity Trends (POET). I. The Eccentricity-Metallicity Trend for Small Planets Revealed by the LAMOST-Gaia-Kepler Sample
arXiv:2303.02941 · doi:10.3847/1538-3881/acb533
Abstract
Orbital eccentricity is one of the basic planetary properties, whose distribution may shed light on the history of planet formation and evolution. Here, in a series of works on Planetary Orbit Eccentricity Trends (dubbed POET), we study the distribution of planetary eccentricities and their dependence on stellar/planetary properties. In this paper, the first work of the POET series, we investigate whether and how the eccentricities of small planets depend on stellar metallicities (e.g., [Fe/H]). Previous studies on giant planets have found a significant correlation between planetary eccentricities and their host metallicities. Nevertheless, whether such a correlation exists in small planets (e.g. super-Earth and sub-Neptune) remains unclear. Here, benefiting from the large and homogeneous LAMOST-Gaia-Kepler sample, we characterize the eccentricity distributions of 244 (286) small planets in single (multiple) transiting systems with the transit duration ratio method. We confirm the eccentricity-metallicity trend that eccentricities of single small planets increase with stellar metallicities. Interestingly, a similar trend between eccentricity and metallicity is also found in the radial velocity (RV) sample. We also found that the mutual inclination of multiple transiting systems increases with metallicity, which predicts a moderate eccentricity-metallicity rising trend. Our results of the correlation between eccentricity (inclination) and metallicity for small planet support the core accretion model for planet formation, and they could be footprints of self (and/or external) excitation processes during the history of planet formation and evolution.
21 pages, 15 figures
References in corpus (11)
- Dynamical Outcomes of Planet-Planet Scattering
- Origins of Eccentric Extrasolar Planets: Testing the Planet-Planet Scattering Model
- Exoplanet Orbital Eccentricities Derived From LAMOST-Kepler Analysis
- On the Eccentricity Distribution of Exoplanets from Radial Velocity Surveys
- The Photoeccentric Effect and Proto-Hot Jupiters I. Measuring photometric eccentricities of individual transiting planets
- Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations
- LAMOST telescope reveals that Neptunian cousins of hot Jupiters are mostly single offspring of stars that are rich in heavy elements
- A Super-Solar Metallicity For Stars With Hot Rocky Exoplanets
- CKS VIII: Eccentricities of Kepler Planets and Tentative Evidence of a High Metallicity Preference for Small Eccentric Planets
- Predicting the frequencies of diverse exo-planetary systems
- On the origin of the eccentricity dichotomy displayed by compact super-Earths: dynamical heating by cold giants