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Gravitational Collapse of Interstellar Magnetized Clouds

星际磁化云的引力塌缩

基本信息

批准号：
07640351
负责人：
TOMISAKA Kohji
金额：
$ 1.41万
依托单位：
Niigata University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07640351/
关键词：
Interstellar Clouds Star Formation Interstellar Magnetic Fields Gravitational Collapse Adaptive Method

项目摘要

The evolution of an isothermal magnetized interstellar cloud was studied with a parallelized magnetohydrodynamics (MHD) code and a fast Poisson solver based on the CGS (conjugate gradient squared) method.Since the density distribution of a cloud in the dynamical contraction phase is central-peaked, the code must have fine spatial resolution near the center, while in the outer part numerical grid must be large. The 'nested grid technique' meets these contradictory conditions. A number of grids are prepared ; finer ones cover only the central part, while coarser ones cover the whole cloud.1.From the numerical simulation using the nested grid method, it is shown that (1) a disk is formed perpendicular to the magnetic field lines, and that (2) the disk evolves in a self-similar manner and the solution reaches a special power-law distribution : for example, the density on the equatorial plane indicates a power-law as p (r) * r^<-2>.2.In a finite time, the solution becomes singular. After the epoch, matter begins to accrete onto a central body with a finite mass. This is studied using a sink cell method. (1) From this, it is shown that an outward-facing shock front is formed in the disk in the accretion phase. Infalling matter is stopped at the shock surface and is accelerated again. (2) The mass accretion rate is much larger than the standard rate obtained by Shu.

采用并行磁流体动力学（MHD）程序和基于共轭梯度平方（CGS）方法的快速Poisson求解器研究了等温磁化星际云的演化过程，由于动力学收缩阶段云的密度分布是中心峰值的，因此程序在中心附近必须有很好的空间分辨率，而在外部必须有较大的数值网格。“嵌套网格技术”满足这些矛盾的条件。采用嵌套网格方法进行数值模拟，结果表明：（1）在垂直于磁力线的方向上形成一个圆盘，（2）圆盘以自相似的方式演化，解满足幂律分布：例如，赤道平面上的密度表示幂律为p（r）* r^<-2>。2.在有限时间内，解变得奇异。在纪元之后，物质开始附积到具有有限质量的中心体上。这是研究使用一个汇细胞的方法。(1)由此可见，在吸积阶段，盘中形成了一个向外的激波阵面。下落的物质在激波表面停止并再次加速。(2)质量吸积率比舒得到的标准吸积率大得多。