The Parker Instability in a Thick Gaseous Disk. II. Numerical Simulations in Two Dimensions
The Parker Instability in a Thick Gaseous Disk. II. Numerical Simulations in Two Dimensions
复制标题
厚气盘中的帕克不稳定性。
DOI：
10.1086/317782
复制
发表时间：
2000
期刊：
影响因子：
--
通讯作者：
D. Ryu
中科院分区：
文献类型：
--
作者：
A. Santillán;Jongsoo Kim;J. Franco;M. Martos;S. Hong;D. Ryu
我们提出了多分量热盘模型中 Parker 不稳定性的二维理想 MHD 数值模拟。计算是使用两种具有不同算法的数字代码（TVD 和 ZEUS-3D）完成的。使用这两种代码进行的数值实验的结果非常相似，并证实了先前工作中得出的波状模线性分析的结果：最不稳定的波长约为 3 kpc，其增长时间尺度在 30 到 50 Myr 之间（增长速率对数值网格上边界的位置敏感）。因此，该多分量盘模型的时间和长度尺度远大于薄盘模型的时间和长度尺度。我们使用三种不同类型的扰动（随机、对称和反对称）来触发不稳定性。反对称模式占主导地位，决定了非线性状态开始的最短时间。这种不稳定性会产生密集的凝聚，而反对称情况下的最终峰值柱密度值（也是由 Kim 和同事得出的）大约是其初始值的 3 倍。这些波长和密度增强因子表明，单独的不稳定性不能成为一般星际介质中巨分子云的主要形成机制。简要讨论了沿旋臂形成大规模波纹时不稳定性的作用。
We present two-dimensional, ideal-MHD numerical simulations of the Parker instability in a multicomponent warm disk model. The calculations were done using two numerical codes with different algorithms, TVD and ZEUS-3D. The outcomes of the numerical experiments performed with both codes are very similar and confirm the results of the linear analysis for the undular mode derived in a previous work: the most unstable wavelength is about 3 kpc and its growth timescale is between 30 and 50 Myr (the growth rate is sensitive to the position of the upper boundary of the numerical grid). Thus, the time and length scales of this multicomponent disk model are substantially larger than those derived for thin-disk models. We use three different types of perturbations, random, symmetric, and antisymmetric, to trigger the instability. The antisymmetric mode is dominant and determines the minimum time for the onset of the nonlinear regime. The instability generates dense condensations, and the final peak column density value in the antisymmetric case, as also derived by Kim and coworkers, is about a factor of 3 larger than its initial value. These wavelengths and density enhancement factors indicate that the instability alone cannot be the main formation mechanism of giant molecular clouds in the general interstellar medium. The role of the instability in the formation of large-scale corrugations along spiral arms is briefly discussed.
R.Matsumoto：“非均匀引力场中的非线性帕克不稳定性：非线性振荡和冲击波”Astrophys.J.(1990)
DOI：
--
发表时间：
--
期刊：
影响因子：
--
作者：
通讯作者：
--