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Title: Planet formation - architectures, theory
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Authors:
Shigeru Ida (Tokyo Institute of Technology)

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Abstract:
I will review planet formation theory, based on core accretion scenario for gas giant planets, focusing on connection with observations of protoplanery disks and extrasolar planets. Planetesimal accretion to form terrestrial planets and cores of gas giants, gas accretion onto the cores, orbital migration of giant planets to form “hot jupiters”, and orbital instability of giant planets to form “eccentric planets” are discussed. In general, formation of gas giants is favored in the regions just beyond an ice boundary. The formation of gas giants is inhibited by small core isolation mass in inner regions and by slow core growth in outer regions. In massive disks, gas giants can form well before deletion of disk gas, resulting in hot jupiters through the migration. More than 3 gas giants can also co-exist, resulting in eccentric planets through the orbital instability. In disks similar to the minimum mass solar nebula, only one or two gas giants form on timescales comp!
arable to disk lifetime, so that they tend not to undergo orbital migration and instability. With the available data for distribution of disk mass, mass and orbital radius distribution of planets is predicted and compared with observation of extrasolar planets. Our model accounts for the observed dependence on metallicity of host stars. The dependence on mass of host stars is also predicted. For example, Neptune mass planets may be much more common than Jupiter mass planets around M stars, if disk mass is significantly lower than that around FGK stars.

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