[P-PS06] Planetary Sciences

[PPS06-02] Stellar mass dependence of planetary systems formed by giant impacts: minimum-mass exstrasolar nebula model and habitable planets

*Haruka Hoshino^1,2, Eiichiro Kokubo^2,1 (1.Department of Astronomy, Graduate School of Science, The University of Tokyo, 2.Division of Science, National Astronomical Observatory of Japan)

Keywords:planetary system formation, terrestrial planet, giant impact, stellar mass

Recent exoplanet surveys revealed that for solar-type stars close-in super-Earths are ubiquitous and many of them are in multi-planet systems. These systems are more compact than the solar system’s terrestrial planets. Ongoing and future exoplanet observations will find more planets around low-mass stars. However, there are not many theoretical studies on the formation of such planets around low-mass stars. Now is the time to clarify the dependence of the stellar mass on planet formation. In the standard model, the final stage of terrestrial planet formation is the giant impact stage where protoplanets gravitationally scatter and collide with each other, to evolve into a stable planetary system. We investigate the effect of the stellar mass on the architecture of planetary systems formed by giant impacts. We perform N-body simulations of the giant impact stage around different stellar masses. Using the minimum-mass extrasolar nebula model, we set the isolation mass of protoplanets and distribute them in 0.05 - 0.15 au from the central star. We follow the evolution for 200 million orbital periods of the innermost planet. We find that the eccentricity and inclination of orbits, and the orbital separation of adjacent planets increase with decreasing the stellar mass. This is because that as the stellar mass decreases the relative strength of planetary scattering becomes more effective. We also discuss the properties of planets formed in the habitable zone.