| Project/Area Number |
62540186
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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 | Nagoya University |
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Principal Investigator |
FUJIMOTO Mitsuaki Department of Physics, Nagoya University, 理学部, 教授 (70022580)
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| Co-Investigator(Kenkyū-buntansha) |
HANAWA Tomoyuki Department of Physics, Nagoya University, 理学部, 助手 (50172953)
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| Project Period (FY) |
1987 – 1988
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| Project Status |
Completed (Fiscal Year 1988)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1988: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1987: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Bisymmetric Spiral Magnetic Fields / Turbulent Diffusion / Dynamo / GMCs / Velocity Dispersion / Rotating Ellipsoids / ダイナモ / 乱流拡散 / 分子雲 / 銀河中心核 |
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| Research Abstract |
1. Bisymmetric spiral (BSS) magnetic fields in spiral galaxies are reproduced by using turbulent diffusion and dynamo regeneration of mean fields in the galactic gaseous disk. The BSS magnetic fields progate and rotate as a wave over large area of the disk. The angular velocity of the BSS magnetic field pattern is found to be approximately equal to that of the spiral density wave, and thus the quasi-resonant magnetogravitational interaction occurs between these two waves. Generation and maintenance of the spiral density waves are controlled by the BSS magnetic fields.
2. A mathematical technique is developed to follow nonlinear motions of rotating gaseous ellipsoids in external force fiels. It is widely applied to various problems such as magnetized rotating gaseous clouds in the galactic tidal force, neutron stars emitting gravitational waves etc.. In the present research program, we followed nonaxisymmetric large-amplitude oscillation of rotating interstellar gas cloud in gravitational contraction. We are now searching for a possible relation between this violent oscillation of rotating gas cloud and star formation activities.
3. We have simulated gravitational interaction between stars and giant molecular clouds using the nearest neighbour approximation. Stars are randomly accelerated, but a resultant kinetic energy is used mostly to migrate systematically inward or outward on the galactic plane: Only a small portion of the energy is stored as that of the random motion on the local galactic circular motion. The random velocity of 【.Itorsim.】50 kms<@D1-1@>D1 of population I stars can be reproduced by the gravitational interaction with giant molecular clouds, but that【greater than or equal】 50 kms<@D1-1@>D1 must be due to other notyet-identified mechanisms.
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