| Project/Area Number |
61540173
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
TOSA Makoto Tohoku University, Faculty of Science, 理学部, 助教授 (50022728)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1987: ¥400,000 (Direct Cost: ¥400,000)
Fiscal Year 1986: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Keywords | Computer Simulation / Dwarf Galaxy / Galactic Evolution / Galaxy / Gas Cloud / Mass Ejection / Shock Wave |
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| Research Abstract |
1. Stability and dynamics of an uniform self-grvitating gas cloud with energy source and dissipation is studied as a model of starfoming gas clouds. Stable equilibrium state is realized in a very narrow range of a parameter characterizing star formation. Viscosity suppresses growth of overstable oscillations and leads the oscillation to limit cycles. Nature of the nonlinear oscillation sensitively depends on the time lag of energy input due to star formation; as the time lag increases the limit cycle becomes unstable resulting in chaotic states of oscillation.
2. Evolution of shock waves induced by compression of a gas cloud by star formation is considered. The shock wave sweeps the gas to form a thin compressed gas shell converging toward the cloud center. The shell becomes gravitationally unstable and breaks into fragments before the cloud collapses as a whole. This provides a mechanism of formation of a stellar association in a molecular gas cloud. Effect of perturbation on a shock wave is studied. If a shock front is distorted by some perturbation, the shocked gas accumulated at the bottoms of the distorted front to form strong gas concentration. Although this process is transient phenomena, it is important for a mechanism of formation of gas condensation in molecular gas clouds and star formation.
3. Evolution of dwarf elliptical galaxies (dEs) is considered with special attention to mass loss due to star formation. The observed properties dEs are naturally explained if significant fraction of the total mass had been lost in its early phase of evolution. if the gas is lost mainly from central region of the system, the central concentration of the system decreases in agreement with the observed structure.
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