Stellar mass dependence of the planetary system formed by giant impact

Speaker: Haruka Hoshino (U. of Tokyo, *Student talk)


Recently, much attention has been paid to planet formation in stars that are lighter than the Sun, especially M-type stars. So far, many so-called super-Earths, which are about ten times the mass of the Earth, have been discovered. These planets have been found relatively close to the central star, about 0.01-0.5 AU, and are known to be very compact in the case of multiple-planet systems. This feature is not found in terrestrial planets in the solar system, which is also a multiple-planet system. Besides, low-mass stars such as M-type stars have a habitable zone close to the star where liquid water can exist on the surface, so there is a high probability that terrestrial planets will be found within the habitable zone. However, until now, there have been few systematic studies on the effect of the mass of the central star on the planetary system. In particular, the orbital structure of the planetary system has not been investigated much. Therefore, we have been investigating the dependence of the orbital structure of planets on the central star mass. In our previous research, we confirmed that the orbital structure of planets becomes more unstable when the central star mass is small, and more collisions occur. However, the disk model was not sufficient, so we improved it this time.  We have developed a new disk model according to the MMEN model and studied the process of giant impact of protoplanets in N-body simulations.