1999 Fiscal Year Final Research Report Summary
The origin of diversity of extrasolar planets formation of giant gasous planets and orbital evolution
| Project/Area Number |
09440089
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Astronomy
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
NAKAZAWA Kiyoshi Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Professor, 大学院・理工学研究科, 教授 (10025455)
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| Co-Investigator(Kenkyū-buntansha) |
EMORI Hiroyuki Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Research Associate, 大学院・理工学研究科, 助手 (30262257)
WATANABE Seiichiro Department of Earth and Planetary Physics, University of Nagoya, Associate Professor, 大学院・理工学研究科, 助教授 (50230967)
IDA Shigeru Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Associate Professor, 大学院・理工学研究科, 助教授 (60211736)
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| Project Period (FY) |
1997 – 1999
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| Keywords | solar system / jovian planets / terrestrial planets / extrasolar planets / protoplanetary disk / orbital stability / celestial mechanics / numerical simulation |
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| Research Abstract |
About 30 extrasolar planets have been discovered since 1995. They would be giant planets like Jupiter and Saturn in the Solar system, because the present detection method limits planet mass that can be detectable. About half of them have very short orbital period (shorter than that of Mercury), while the other half have large orbital eccentricity. We have tried to explain the diversity of the extrasolar planets by generalizing the standard theory of the Solar system.
This year, we investigated the formation of giant planets and their orbital stability more deeply. Giant planets are formed as follows a solid core with about 10 earth masses accretes from planetesimals and gas of a protoplanetary disk is captured by strong gravity of the core to form massive envelope. We investigated
(1) the dependence of formation of a solid core on mass of a protoplanetary disk,
(2) time scale of gas infall onto the core, and
(3) orbital stability of giant planets in the protoplanetary disk.
Regarding (1), we found that in a massive protoplanetary disk, gas giant planets can be formed in inner region. Regarding (2), we found that gas infall can start at less massive core mass than so far considered, but the time scale of gas infall is rather long. Regarding (3), we found that gas drag generally stabilizes the orbits, but the effect is weak if separation distance between the planets is smaller than some critical value. From these results, we conclude that generalization of the standard theory of the Soalr system to different mass protoplanetary disks would account for the diversity of the extrasolar planets.
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