S20A0138abst
S20A0138
The first exoplanet discovered in 1995 was 51 Peg b and we know the exoplanet as a Hot Jupiter (HJ). The formation mechanism of HJs is not fully understood yet, although many HJs have been discovered by Doppler and transit methods and various properties of HJs have been uncovered so far. Two distinct mechanisms to form HJs in a standard model of the planet formation scenario have been proposed; 1) Gas disk migration (GDM) and 2) Gravitational scattering and tidal interaction (so called High eccentricity migration, HEM). One of the most essential differences between the two mechanisms is "time-scale". GDM takes place together with a planetary formation in the protoplanetary disk for first βΌ10 Myr. HEM occurs after orbital instabilities of giant planets, and thus takes more than several hundred Myr. In this proposal, we propose a precise Doppler survey of solar-type stars in Pleiades open cluster to confirm the time-scale of the HJ formation using the HDS/Subaru. The age of Pleiades cluster is estimated to be about 140 Myr and gravitationally scattered giant planets in the Pleiades have not been affected by the tidal interaction yet. Thus, if we confirm existences of HJs in the Pleiades cluster, a formation mechanism of the HJs would be GDM.
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