Instability of magnetized and differentially rotating stellar radiation zones with high magnetic Mach number
Instability of magnetized and differentially rotating stellar radiation zones with high magnetic Mach number
复制标题
高磁马赫数磁化和差动旋转恒星辐射区的不稳定性
DOI：
10.1093/mnras/stv2838
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发表时间：
2016
影响因子：
4.8
通讯作者：
Kitchatinov
中科院分区：
文献类型：
--
作者：
Rüdiger;Schultz;Kitchatinov
与应用程序内太阳型辐射区，线性理论被用来分析的不稳定性的环形背景场的偶极宇称，在存在的密度分层，差分旋转和现实小普朗特数。物理参数为阿尔文频率ΩA、全球自转速率Ω和浮力频率N（ΩA< Ω <N）。仅考虑具有最大增长率的波长的解。如果把这些尺度结合起来估计径向速度，人们发现它几乎不依赖于纬向切变和磁马赫数。在Schatzman的公式中，化学物质的径向混合可以被估计为Re* = O（100），这确实是在1 Gyr的时间尺度上耗散太阳速跃层中的锂所必需的。计算的增长率表明，除了小的马赫数和反日切变外，随着纬向切变的增长，系统不稳定。不稳定模式的磁能和动能之比ε仅轻微取决于剪切力，但对磁马赫数有很强的依赖性，其中ε ‡ Mm2。有效磁普朗特数达到O（103），因此，对于高磁马赫数的恒星，差旋的衰减速度比环形背景场快得多。
With applications to inner solar-type radiative zones, a linear theory is used to analyse the instability of a toroidal background field of dipolar parity, in the presence of density stratification, differential rotation and realistically small Prandtl numbers. The physical parameters are the Alfvén frequency ΩA, the global rotation rate Ω and the buoyancy frequencyNwith ΩA< Ω <N. Only the solutions for the wavelengths with the maximal growth rates are considered. If these scales are combined to estimate radial velocities, one finds that it hardly depends on the latitudinal shear and the magnetic Mach number. In the formulation of Schatzman the radial mixing of chemicals can be estimated as Re* = O(100) which indeed is necessary to dissipate the lithium in the solar tachocline with a time-scale of 1 Gyr. The calculated growth rates indicate adestabilizationof the system for growing latitudinal shear except for small Mach numbers and antisolar shear. The ratio ε of the magnetic and the kinetic energy of the instability pattern only slightly depends on the shear but a strong dependence on the magnetic Mach number exists with ε ∝ Mm2. The effective magnetic Prandtl number reaches values O(103) so that for the stars with high magnetic Mach number the differential rotation decays much faster than the toroidal background field.