| Project/Area Number |
07640346
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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) |
1995 – 1996
|
| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1995: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | GALAXIES / INTERSTELLAR GAS / DYNAMICAL EVOLUTION / 恒星系力学 |
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| Research Abstract |
Dynamical evolution and activities of gas-rich galazies have been investigated by numerical simulations which include interstellar gas and star formation process. First, the dynamical interactions between the Galaxy, Large and Small Magellanic Clouds have been examined as a case study. Second, mergers between large elliptical galaxies and small disk galaxies have been simulated. The second half of this research project has been focused on how the gravity of the interstellar gas affects the dynamical evolution of isolated galaxies. It was found that the amount of the gas existent in the early evolutionary phase strongly affects the occurrence of non-axisymmetric structures, especially bars. The initial gas amount itself is determined by the timescale of disk formation. This result leads to a unified picture that the bars of early-type galaxies have been created by galaxy-galaxy encounters, whereas the late-type galaxies have developed their bars spontaneously by the gravitational instability of the disk. Simulations have been performed also on the collapse of protogalaxies and subsequent formation of disk galaxies. This research resulted into a new evolution model, in which the copious interstellar gas contained in the early disk forms massive clumps due to gravitational instability, and these clumps act as the major driving force of the evolution. This model explains peculiar morphology and photometric characteristics of young galaxies, and provides a new picture on the causal relationship between the emergence of activities such as quasars and the dynamical evolution of host galaxies.
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