Magnetic braking of an aligned rotator during star formation: An exact, time-dependent solution
Magnetic braking of an aligned rotator during star formation: An exact, time-dependent solution
复制标题
恒星形成过程中对齐旋转体的磁制动：精确的、与时间相关的解决方案
DOI：
10.1086/157936
复制
发表时间：
1980
期刊：
影响因子：
--
通讯作者：
E. Paleologou
中科院分区：
文献类型：
--
作者：
T. Mouschovias;E. Paleologou
在以前的论文中，我们研究了角动量和磁场矢量相互垂直的刚性旋转星际云（或碎片）的磁制动。现在我们讨论一个盘状云（密度为rhol）的情况，它的角动量和初始磁场与对称轴成一直线。云（或碎片）被赋予相对于外部介质（密度为ρ/sub ext/）的初始角速度。然后，角速度和磁场的计算作为空间和时间的函数在磁盘和外部介质。严格地确定了非线性扭转阿尔芬波的大量内反射效应，并给出了物理解释。初始条件和不连续的角速度在整个磁盘表面进行了研究，这两种情况下进行了比较与一个解决方案的刚性旋转磁盘。虽然云结构的瞬态响应在三种情况下是非常不同的，由云作为一个整体的多余的角动量的损失是不敏感的初始条件，可以准确地表示由刚性转子模型，如果比率rho/sub cl//rho/sub ext/不接近1。
In a previous paper we studied the magnetic braking of a rigidly rotating interstellar cloud (or fragment) whose angular momentum and magnetic field vectors were mutually perpendicular. We now discuss the case of a disk cloud (of density rhol) whose angular momentum and initial magnetic field are aligned with the axis of symmetry. The cloud (or fragment) is imparted an initial angular velocity with respect to the external medium (of density rho/sub ext/). The angular velocity and magnetic field are then calculated as functions of space and time in both the disk and the external medium. The effect of the numerous internal reflections of nonlinear torsional Alfven waves in determined rigorously and explained physically. Initial conditions with and without a discontinuity in angular velocity across the disk surfaces are studied, and both cases are compared with a solution for a rigidly rotating disk. Although the transient response of the cloud structure is very different in the three cases, the loss of excess angular momentum by the cloud as a whole is insensitive to the initial conditions and can be accurately represented by the rigid rotator model if the ratio rho/sub cl//rho/sub ext/ is not close to unity.