Speaker: Sho Shibata (UZH)
Title: 
Evolution in chemical composition of gas giant planets: the effects of planetesimal accretion
Abstract: 
After the discovery of exoplanets, the planetary formation theory has changed to consider the effect of dynamic orbital evolution of planets, such as a planetary migration triggered by the tidal interaction with disk gas. The planetary migration complicates the evolution paths of gas giant planets and makes it difficult to retrieve the formation history of gas giant planets from observations. To solve the complex evolution paths of gas giant planets, we need to know the evolution in chemical composition of gas giant planets.
Recent studies reveal the chemical composition of close-in gas giant planets and obtain the total amount of heavy elements contained in those planets. In our study, we focused on a planetesimal accretion, which is considered as one of the main processes of heavy elements accretion, and tried to constrain the formation paths of gas giant planets. Using the N-body integration of planetesimals, we found that the planetesimal accretion occurs in gas accretion phase and planetary migration phase efficiently, and in planetary migration phase the mean motion resonances control the accretion rate of planetesimals. In the massive protoplanetary disk, heavy elements up to a few hundreds Earth-masses can be captured by a gas giant planet. These results suggest that highly polluted close-in gas giant planets migrated more than tens-AU and some of those planets might form via gravitational instability. To constrain the formation paths of gas giant planets more strongly, we need to consider more detailed chemical compositions, such as C/O ratio.