2001 Fiscal Year Final Research Report Summary
Mecanism of Outflow form Dynamically Contracting Molecular Cores
| Project/Area Number |
11640231
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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 | National Astronomical Observatory Of Japam (2000-2001)
Niigata University (1999) |
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Principal Investigator |
TOMISAKA Kohji National Astronomical Observatory Of Japam theoretical Astrophysics Divisiom Professor, 理論天文学研究系, 教授 (70183879)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAMURA Fumitaka Faculty of Education and Human Sciences,Niigata University Department of Physics,Associate Professor, 教育人間科学部, 助教授 (20291354)
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| Project Period (FY) |
1999 – 2001
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| Keywords | Interstellar Molecular Clouds / Star Formation / Outflow / Dynamical Cotraction / Nested Grid Method / Self-Similar Evolutions |
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| Research Abstract |
Dynamical contraction of interstellar molecular clouds is studied. 1. Tomisaka studied the mechanism of molecular outflow with the nested-grid axi-symmetric magnetohydrodynamical simulations. Rotations of the molecular cloud cores amplify the toroidal magnetic fields, which eject the gas as molecular outflows. From the simulations, we explored the followings : (1) Initial rotation speed specifies the epoch when the molecular outflow begins. That is, increasing the angular momentum, the outflow is launched immediate after the adiabatic core is formed. (2) When the initial poloidal magnetic field is strong (its energy is comparable to the thermal one), a U-shaped outflow is formed, in which gas is mainly outflowing through a region whose shape looks like a capital letter U at a finite distance from the rotation axis. (3) The other is a turbulent outflow in which magnetic field lines and velocity fields seem to be randomly oriented, which is realized when the initial magnetic energy is much smaller than the thermal one. In this case, globally the gas moves out almost perpendicularly from the disk and the outflow looks like a capital letter I. 2. Nakamura studied the gravitational collapse of a cloud supported by strong magnetic fields taking into account of the magnetic diffusion. (1) A model with large mass leads to fragmentation to a number of high-densitycores in the early phase. This corresponds to a cluster forming mode. (2) Incontrast, in a less massive cloud a bar grows and the bar breaks into fragments. In this case a binary system will appear.
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