1997 Fiscal Year Final Research Report Summary
Planetary Formation relevant to Titius-Bode's Law
| Project/Area Number |
07454114
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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 |
Space and upper atmospheric physics
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| Research Institution | TOKYO INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
NAKAZAWA Kiyoshi Graduate School of Science and Engineering, 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) |
OHTSUKI Keiji Faculty of Science, Yamagata University, Research Associate, 理学部, 助手 (00250910)
EMORI Hiroyuki Graduate School of Science and Engineering, Tokyo Institute of Technology, Resea, 大学院・理工学研究科, 助手 (30262257)
IDA Shigeru Graduate School of Science and Engineering, Tokyo Institute of Technology, Assio, 大学院・理工学研究科, 助教授 (60211736)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Planetary Formation Process / Terrestrial Planets / accumulation process / Jovian Planets |
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| Research Abstract |
In the last decade great efforts have been dedicated to solve two big problems in studies for planetary formation processes. One problem is that we could not explain the formation of Jovian planets. such as Jupiter and Saturn in the proto solar nebula which is considered to dissipate in a very little time as equal as about ten million years. And another is that we could not explain present distances between planets.
Until now a sequence of the planetary formation that terrestrial planets orbiting near the Sun accumulated faster than the Jovian planets in the distant orbit from the Sun has been accepted. To consider the two big problems we abandoned this preconception and adopt a new working hypothesis that the Jovian planets are formed before the terrestrial planets are accumulated. We consider that strong gravity from the Jovian planets are necessary to reproduce present arrange of the terrestrial planets.
At first, to adopt the working hypothesis it is necessary to consider the formati
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on process of the Jovian planets. To produce a Jovian planet which has great amount of hydrogen gas a solid core should accumulate in the proto solar nebula and become large enough to attract gas from nebula by it's gravity. The minimum mass of the solid core to attract gas from solar nebula was believed to be about 10 times earth's mass. It is very difficult to produce such large solid core in the present Jupiter region within ten million years. We studied the accumulation process of a solid ore and the gas capturing process by the core. Summarizing the result we conclude as follows.
(1) It is possible to produce a solid core with few tines earth's mass at present Jupiter's orbit in ten million years.
(2) Owing to the decline of the planetesimal accumulation rate to the solid core in the last stage of it's growth a solid core with only few times earth's mass can attract gas from the proto solar nebula.
From thses results we conclude that jovian planets are possibily accumulated before present terrestrial planets are formed. So, the necessity to investigate the late stage accumulation of the terrestrial plates under the effect of strong gravity from the Jovian planets increases. Less
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