Dependence of Planet Populations on Stellar Mass and Metallicity: A Pebble-accretion-based Planet Population Synthesis Model

Abstract

The formation and evolution of planetary systems are linked to their host stellar environment. In this study, we employ a pebble-accretion-based planet population synthesis model to explore the correlation between planetary properties and stellar mass/metallicity. Our numerical results reproduce several main aspects of exoplanetary observations. First, we find that the occurrence rate of super-Earths, η _SE , follows an inverted V-shape in relation to stellar mass: it increases with stellar mass among lower-mass dwarfs, peaks at early M dwarfs, and declines toward higher-mass GK stars. Second, super-Earths grow ubiquitously around stars with various metallicities, exhibiting a flat or weak η _SE dependence on Z _⋆ . Third, giant planets in contrast form more frequently around stars with higher mass/metallicity. Lastly, we extend a subset of simulations to 1 Gyr to investigate the long-term evolution of the systems’ architecture. By converting our simulated systems into synthetic observations, we find that the eccentricities and inclinations of single-transit systems increase with stellar metallicity, while these dependencies in multiplanet systems remains relatively weak. The alignment between our results and observations provides key insights into the connection between planet populations and stellar properties.

Keywords

• Exoplanet dynamics
• Exoplanets
• Exoplanet systems
• Exoplanet migration
• Exoplanet formation