The origin of the hot planets: The slingshot model

Abstract

We studied the origin of short-period planets by numerical simulations.
Many short-period Jovian or Neptunian planets are discovered outside of the solar system. One proposed mechanism for the formation of short-period planets is a slingshot model. In this model, a planet is scattered into shorter orbit by close encounters of the planets, and the dynamic tide from the central star makes the planet be short-period.
We performed numerical simulations to test the efficiency of the slingshot model. Although the planet cannot be scattered into the short-orbit directly, we found that the Kozai mechanism effectively make the short-period planets, especially when more than three planets are left in the system. In our simulation, the short-period planets are formed at about 20-30% cases after the planet-planet scatterings.