Numerical Study on Evolution from Magnetized Cloud to Protostar Using Three-Dimensional Nested Grid Method
| Project/Area Number |
14540233
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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 Japan |
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Principal Investigator |
TOMISAKA Kohji National Astronomical Observatory, 理論研究部, 教授 (70183879)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMOTO Tomoaki Hosei University, Faculty of Human Environment, 人間環境学部, 助教授 (60308004)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | star formation / interstellar magnetic field / rotation motion / magnetorotational centrifugal wind / binary stars / gravity / fragmentation / 連星・多重星 / 数値計算法 |
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| Research Abstract |
Using three-dimensional magnetohydrodynamical (NM) simulations, the contraction of the interstellar loud and star formation are studied for the density range from 102 to 1012 cm3.
1. In the nested grid method, a number of grid systems are used. Fine grids cover the high-density center while coarse grids cover the low-density envelope, which guarantees the numerical accuracy in the simulation of self-gravitational collapse. MHD simulation programs (2-dimensional and 3-dimensional) based on the nested grid method was developed, in which the Poisson equation of the self gravity is solved with a multigrid iteration method modified for the nested grid.
2. Axisymmetric 2D simulations show that a disk extending perpendicular to the magnetic field is made and that after the adiabatic core forms at the center with a density of〜10^10 cm-3 gas is ejected perpendicular to the disk owing to the angular momentum transport from the core to the flow.
3. Three-dimensional MHD simulations found three diffe
… More
rent evolutions for the adiabatic core which will form new-born stars.
(1) Spiral density wave develops in the adiabatic core. High-density (at least two) parts of the arms contract and form binary protostars (spiral fragmentation).
(2) In the isothermal disk, nonaxisymmetric perturbations grow and form bar structure. High-density parts of the bar-shaped adiabatic core collapse by the self-gravity and binary protostars form in the bar (bar fragmentation).
(3) The adiabatic core never fragment and a centrally-peaked core continues to contract and form a single protostar (nofragmentation).
4. Condition for fragmentation is obtained as the ratio of the angular rotation speed to the magnetic flux density is larger than 3 times 10-7 y-1 micro G-1.
5. Even if the initial rotation vector is not parallel to the magnetic field, magnetic field and rotation vector becomes to be aligned each other near the center of the cloud in the course of contraction. A disk runs in the perpendicular direction to the local magnetic field. Less
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Report
(4 results)
Research Products
(18 results)
