Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
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.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
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
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
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.
Peer Review Status:Awaiting Review
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