Stationary perturbation configurations in a composite system of stellar and coplanarly magnetized gaseous singular isothermal discs
Stationary perturbation configurations in a composite system of stellar and coplanarly magnetized gaseous singular isothermal discs
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恒星和共面磁化气态奇异等温盘复合系统中的稳态扰动配置
DOI：
10.1111/j.1365-2966.2004.07501.x
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发表时间：
2003
影响因子：
4.8
通讯作者：
Y. Zou
中科院分区：
文献类型：
--
作者：
Y. Lou;Y. Zou
我们构建对齐和非对齐的固定扰动配置在一个复合系统的恒星和共面磁化气体奇异等温盘（SID）耦合重力。这项研究扩展了Shu等人最近对（磁化）SID的分析，卢和卢和沈。通过这个模型，我们打算提供一个概念框架，以获得多波长的盘星系的大尺度结构观测的见解。这两个小岛屿发展中国家近似剃刀薄，并在一个自洽的轴对称背景平衡与幂律表面质量密度和平坦的旋转曲线。气体SID嵌入有径向标度为r-1/2的共面方位磁场B θ（r），该磁场不是无力的。与以前研究的SID问题相比，有三种可能的静态解决方案允许更多的动态自由。为了确定物理解，我们探索了包含三个无量纲参数的参数空间：磁化气体SID中的阿尔芬速度与声速之比λ;恒星速度色散的平方与气体声速之比β;以及两个SID的表面质量密度之比δ。对于具有方位角周期性的对准和非对准螺旋情况，|M|当β ≥ 2时，三个解分支中的一个总是物理解，而当β超过某个临界值时，另外两个解分支可能失效。对于从轴对称平衡到定向长期棒状不稳定性的起始判据，相应的T/|W - M|随λ、β和δ变化的比值可能大大低于经常引用的T/δ值。|W|其中T是总动能，W是总重力势能，M是总磁能。对于非对齐螺旋的情况下，我们检查边缘不稳定性的轴对称（|M| 0）和非轴对称（|M|> 0）干扰。由此产生的边际稳定性曲线不同于以前的。复合部分磁化SID系统的情况下，还调查了包括轴对称暗物质晕的SID平衡的引力效应。我们进一步研究了两个SID的质量密度和方位磁场扰动之间的相位关系。我们的精确的全局摄动解和临界点是有价值的测试数值磁流体动力学代码。对于银河系的应用，我们的模型分析包含更现实的元素，并提供了有用的见解盘星系组成的恒星和磁化气体的结构和动力学。
We construct aligned and unaligned stationary perturbation configurations in a composite system of stellar and coplanarly magnetized gaseous singular isothermal discs (SIDs) coupled by gravity. This study extends recent analyses on (magnetized) SIDs by Shu et al., Lou and Lou & Shen. By this model, we intend to provide a conceptual framework to gain insights for multiwavelength large-scale structural observations of disc galaxies. Both SIDs are approximated to be razor thin and are in a self-consistent axisymmetric background equilibrium with power-law surface mass densities and flat rotation curves. The gaseous SID is embedded with a coplanar azimuthal magnetic field B θ (r) of a radial scaling r -1/2 that is not force-free. In comparison with the SID problems studied earlier, there are three possible classes of stationary solutions allowed by more dynamic freedoms. To identify physical solutions, we explore parameter space involving three dimensionless parameters: ratio λ of Alfven speed to sound speed in the magnetized gaseous SID; ratio β of the square of the stellar velocity dispersion to the gas sound speed; and ratio δ of the surface mass densities of the two SIDs. For both aligned and unaligned spiral cases with azimuthal periodicities |m| ≥ 2, one of the three solution branches is always physical, while the other two branches might become invalid when β exceeds certain critical values. For the onset criteria from an axisymmetric equilibrium to aligned secular bar-like instabilities, the corresponding T/|W - M| ratio, which varies with λ, β and δ, may be considerably lower than the oft-quoted value of T/|W| ∼ 0.14, where T is the total kinetic energy, W is the total gravitational potential energy and M is the total magnetic energy. For unaligned spiral cases, we examine marginal instabilities for axisymmetric (|m| = 0) and non-axisymmetric (|m| > 0) disturbances. The resulting marginal stability curves differ from the previous ones. The case of a composite partial magnetized SID system is also investigated to include the gravitational effect of an axisymmetric dark matter halo on the SID equilibrium. We further examine the phase relationship among the mass densities of the two SIDs and azimuthal magnetic field perturbation. Our exact global perturbation solutions and critical points are valuable for testing numerical magnetohydrodynamic codes. For galactic applications, our model analysis contains more realistic elements and offers useful insights into the structures and dynamics of disc galaxies consisting of stars and magnetized gas.
Gojal Wakhi 的音响系统
DOI：
--
发表时间：
2005
期刊：
東京外国語大学論集 第71号
影响因子：
--
作者：
FURIHATA;Masashi;降幡 正志;降幡 正志;吉枝聡子;吉枝聡子;Satoko YOSHIE;Satoko YOSHIE
通讯作者：
Satoko YOSHIE