Similarity Solution for Formation of a Circumstellar Disk through the Collapse of a Flattened Rotating Cloud
Similarity Solution for Formation of a Circumstellar Disk through the Collapse of a Flattened Rotating Cloud
复制标题
通过扁平旋转云塌陷形成星周盘的相似解
DOI：
10.1086/305093
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Hanawa
中科院分区：
文献类型：
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作者：
K. Saigo;T. Hanawa
我们提出了相似的解决方案，描述了失控崩溃的旋转等温盘及其随后的内面向外崩溃。相似解包含声速cs和比角动量与质量之比ω作为模型参数。在逃逸坍缩过程中，盘的表面密度在中心部分几乎是恒定的，而在尾部与半径成反比。当中心表面密度通过塌陷而增加时，中心高表面密度部分收缩其半径。因此，面密度在失控坍缩结束时变为1/r幂律。在随后的由内而外的坍缩阶段，盘有两个部分：一个处于准平衡状态的内部旋转盘和一个动态下落的外部包络。内盘和外壳由冲击波限定。内部圆盘的质量和外缘以恒定的速率增长。吸积率与声速的立方成比例，即，其中G表示引力常数。逃逸坍缩的相似解可以再现旋转或磁化圆盘动力学坍缩的数值模拟。由内向外坍缩的相似解表示离心支撑的星周盘的生长。这个解决方案可以应用于一个原恒星，吸积气体基本上通过磁盘。
We present similarity solutions that describe the runaway collapse of a rotating isothermal disk and its subsequent inside-out collapse. The similarity solutions contain the sound speed cs and the ratio ω of the specific angular momentum to the mass as model parameters. During the runaway collapse, the surface density of the disk is nearly constant in the central part and inversely proportional to the radius in the tail. As the central surface density increases by collapse, the central high surface density part shrinks its radius. Thus the surface density becomes a 1/r power law at the end of runaway collapse. In the subsequent inside-out collapse phase, the disk has two parts: an inner rotating disk in quasi-equilibrium and an outer dynamically infalling envelope. The inner disk and outer envelope are bounded by a shock wave. The mass and outer edge of the inner disk grow at a constant rate. The accretion rate is proportional to the cube of the sound speed, i.e., Ṁ ∝ c3s/G, where G denotes the gravitational constant. The similarity solution of the runaway collapse can reproduce numerical simulations of dynamical collapse of either rotating or magnetized disks. The similarity solution of the inside-out collapse denotes growth of a centrifugally supported circumstellar disk. This solution can apply to a protostar that accretes gas substantially through the disk.