Gravitationally coupled scale-free discs
Gravitationally coupled scale-free discs
复制标题
重力耦合无垢圆盘
DOI：
10.1111/j.1365-2966.2004.08065.x
复制
发表时间：
2004
影响因子：
4.8
通讯作者：
Y. Lou
中科院分区：
文献类型：
--
作者：
Yue Shen;Y. Lou
在两个重力耦合的正压无标度圆盘组成的复合流体系统中，旋转曲线为v r −β，表面质量密度为幂律的α = 1 + 2β，我们在两个圆盘中构造了几类共面定常排列和对数螺旋扰动位形.由于相互重力相互作用，存在两类独立的扰动模式，两个耦合圆盘中的表面质量密度扰动要么同相，要么异相。我们推导出这样的扰动模式存在的分析标准，并显示数值例子。我们计算对齐和螺旋扰动模式系统地探索整个参数制度。对于轴对称m = 0的径向振荡的情况下，有两个不稳定的制度，环破碎和金斯崩溃对应的短和长的径向波长，分别。只有在一定范围内的旋转参数D2（平方的有效旋转马赫数的恒星盘）可以对所有轴对称扰动的复合盘系统是稳定的。与单盘系统相比，耦合双盘系统的稳定性相对于轴对称不稳定性变得更差。我们的研究推广了Syer和特里梅因关于单圆盘和Lou和Shen关于两个耦合奇异等温圆盘的工作。简要讨论了非轴对称不稳定性。这些静态模型的各种大尺度模式和形态可能是有用的背景下，盘星系与酒吧和螺旋或酒吧螺旋。Ke yw ords：wave s-stars：formation-ISM：general-galaxies：kinematics and dynamics-galaxies：spiral-galaxies：structure.
In a composite fluid system of two gravitationally coupled barotropic scale-free discs bearing a rotation curve v ∝ r −β and a power-law surface mass density � 0 ∝ r −α with α = 1 + 2β ,w econstruct classes of coplanar stationary aligned and logarithmic spiral perturbation configurations in the two discs. Owing to the mutual gravitational interaction, there are two independent classes of perturbation modes, with surface mass density disturbances in the two coupled discs being either in phase or out of phase. We derive analytical criteria for such perturbation modes to exist and show numerical examples. We compute the aligned and spiral perturbation modes systematically to explore the entire parameter regime. For the axisymmetric m = 0 case with radial oscillations, there are two unstable regimes of ring fragmentation and Jeans collapse corresponding to short and long radial wavelengths, respectively. Only within a certain range of the rotation parameter D 2 (square of the effective rotational Mach number for the stellar disc) can a composite disc system be stable against all axisymmetric perturbations. Compared with a single-disc system, the coupled two-disc system becomes less stable against such axisymmetric instabilities. Our investigation generalizes the previous work of Syer & Tremaine on the single-disc case and of Lou & Shen on two coupled singular isothermal discs. Non-axisymmetric instabilities are briefly discussed. These stationary models for various largescale patterns and morphologies may be useful in the context of disc galaxies with bars and spirals or barred spirals. Ke yw ords: wave s‐ stars: formation ‐ ISM: general ‐ galaxies: kinematics and dynamics ‐ galaxies: spiral ‐ galaxies: structure.
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