The formation of close-in planets by the slingshot model

摘要

We investigated the efficiency of planet scatterings in producing close-in planets by adirect inclusion of the dynamical tide effect into the simulations. We considered a system consistsof three Jovian planets. Through a planet-planet scattering, one of the planets is sent into shorterorbit. If the eccentricity of the scattered planet is enough high, the tidal dissipation from thestar makes the planetary orbit circular. We found that the short-period planets are formed atabout 30% cases in our simulation and that Kozai mechanism plays an important role. In theKozai mechanism, the high inclination obtained by planet-planet scattering is transformed to theeccentricity. It leads the pericenter of the innermost planet to approach the star close enough fortidal circularization. The formed close-in planets by this process have a widely spread inclinationdistribution. The degree of contribution of the process for the formation of close-in planets willbe revealed by more observations of Rossiter-McLaughlin effects for transiting planets.