Planet Occurrence Rate Correlated to Stellar Dynamical History: Evidence from Kepler and Gaia

TL;DR

This study investigates how a star's dynamical history, inferred from relative velocities, affects planet occurrence rates using Gaia and Kepler data, revealing significant correlations between stellar motion and planet types.

Contribution

It introduces a novel analysis linking stellar dynamical history to planet occurrence rates, utilizing Gaia-Kepler data and velocity-based star grouping.

Findings

High-V stars have fewer super-Earths and sub-Neptunes.

High-V stars show a higher occurrence of sub-Earths.

High-V stars have fewer hot Jupiters and more warm/cold Jupiters.

Abstract

The dynamical history of stars influences the formation and evolution of planets significantly. To explore the influence of dynamical history on planet formation and evolution from observations, we assume that stars who experienced significantly different dynamical histories tend to have different relative velocities. Utilizing the accurate Gaia-Kepler Stellar Properties Catalog, we select single main-sequence stars and divide these stars into three groups according to their relative velocities, i.e. high-V, medium-V, and low-V stars. After considering the known biases from Kepler data and adopting prior and posterior correction to minimize the influence of stellar properties on planet occurrence rate, we find that high-V stars have a lower occurrence rate of super-Earths and sub-Neptunes (1--4 R$_{\rm \oplus}$, P<100 days) and higher occurrence rate of sub-Earth (0.5--1 R$_{ \oplus}$, P<30 days) than low-V stars. Additionally, high-V stars have a lower occurrence rate of hot Jupiter sized planets (4--20 R$_{\oplus}$, P<10 days) and a slightly higher occurrence rate of warm or cold Jupiter sized planets (4--20 R$_{\oplus}$, 10<P<400 days). After investigating the multiplicity and eccentricity, we find that high-V planet hosts prefer a higher fraction of multi-planets systems and lower average eccentricity, which is consistent with the eccentricity-multiplicity dichotomy of Kepler planetary systems. All these statistical results favor the scenario that the high-V stars with large relative velocity may experience fewer gravitational events, while the low-V stars may be influenced by stellar clustering significantly.