| Project/Area Number |
14540221
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
NOGUCHI Masafumi TOHOKU UNIVERSITY, GRADUATE SCHOOL OF SCIENCE, ASSOCIATE PROFESSOR, 大学院・理学研究科, 助教授 (20241515)
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| Project Period (FY) |
2002 – 2003
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| Project Status |
Completed (Fiscal Year 2003)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2003: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2002: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | GALAXY FORMATION / DISK GALAXIES / NUMERICAL SIMULATION / STELLAR DYNAMICS / 天文学 / 銀河進化 / 国際情報交換 / オーストラリア |
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| Research Abstract |
Formation process was investigated of the disk galaxies formed in the cosmological nu-merical simulation. Special attention was paid to the dynamical evolution of dwarf galaxies which acereted to the already formed host galaxies. After accretion, these dwarfs have been destroyed completely by the tidal force of the host galaxy, and formed a part of its halo. Stellar kinematical analysis of these destroyed dwarf galaxies revealed that the halo stars they produced memorize the kinematics of their progenitor dwarfs and maintain their characteristic velocity, although these stars lose spatial identity.
A separate high resolution numerical simulation investigated the gravitational effects which accreting dwarfs extert on the disk of the host galaxy. It was found that a dwarf galaxy with a mass of 2 x 10^<10> solar masses passing 15 kpc from the center of our Galaxy should produce a large warp in the galactic disk. This result can explain qualitatively the observed distribution of a high-velocity neutral hydrogen cloud (Complex C). However, no dwarf galaxy is observed which has the required oribit, indicating that the Complex C is unlikely to have formed in this way. It was also found that the accretion of the above dwarf galaxy leads to the tidal disruption of the galactic disk, suggesting that no such accretion should have occurred after the galactic disks have formed.
A case study was carried out on the evolution of the Small Magellanic Cloud (SMC), which is one of the accreting dwarfs of our Galaxy. A consistent simulation of the gaseous and stellar components and the star formation process has revealed that the observed distribution of the neutral hydrogen and the existence of young stars in the SMC can be explained as a result of the interaction between the SMC and the Large Magellanic Cloud and our Galaxy.
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