Jeans Gravitational Instability of a Rotating Collisionless Magnetized Plasma with Anisotropic Pressure

IF 0.6 4区 物理与天体物理 Q4 ASTRONOMY & ASTROPHYSICS
A. V. Kolesnichenko
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引用次数: 0

Abstract

The problem of self-gravitational instability of an astrophysical rotating plasma in a strong magnetic field with an anisotropic pressure tensor is studied on the basis of the Chew–Goldberger–Low (CGL) quasi-hydrodynamic equations modified by generalized polytropic laws. Using the general form of a dispersion relation obtained by the normal-mode perturbation method, a discussion is provided of the propagation of small-amplitude perturbation waves in an infinite homogeneous plasma medium for transverse, longitudinal, and oblique directions with respect to the magnetic field vector. It is shown that different polytropic indices and anisotropic pressures not only change the classical Jeans instability condition but also cause the appearance of new unstable regions. Modified Jeans instability criteria are obtained for isotropic MHD equations and anisotropic CGL equations owing to the influence of the polytropic indices on gravitational and firehose instabilities for astrophysical plasma. It is shown that in the case of a longitudinal mode of perturbation wave propagation, the Jeans instability criterion does not depend on uniform rotation. In the case of the transverse propagation regime, the presence of rotation reduces the critical wave number and exerts a stabilizing effect on the growth rate of the unstable regime.

具有各向异性压力的旋转无碰撞磁化等离子体的杰恩斯引力不稳定性
摘要 基于经广义多向定律修正的Chew-Goldberger-Low(CGL)准流体力学方程,研究了强磁场中具有各向异性压力张量的天体物理旋转等离子体的自引力不稳定性问题。利用法向模式扰动法得到的弥散关系的一般形式,讨论了小振幅扰动波在无限均质等离子体介质中相对于磁场矢量的横向、纵向和斜向的传播。研究表明,不同的多向指数和各向异性压力不仅会改变经典的杰恩斯不稳定条件,还会导致出现新的不稳定区域。由于多向指数对天体物理等离子体引力不稳定性和火管不稳定性的影响,得到了各向同性 MHD 方程和各向异性 CGL 方程的修正杰恩不稳定性准则。研究表明,在扰动波纵向传播模式的情况下,Jeans 不稳定性准则与均匀旋转无关。在横向传播机制中,旋转的存在降低了临界波数,并对不稳定机制的增长率产生了稳定作用。
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来源期刊
Solar System Research
Solar System Research 地学天文-天文与天体物理
CiteScore
1.60
自引率
33.30%
发文量
32
审稿时长
6-12 weeks
期刊介绍: Solar System Research publishes articles concerning the bodies of the Solar System, i.e., planets and their satellites, asteroids, comets, meteoric substances, and cosmic dust. The articles consider physics, dynamics and composition of these bodies, and techniques of their exploration. The journal addresses the problems of comparative planetology, physics of the planetary atmospheres and interiors, cosmochemistry, as well as planetary plasma environment and heliosphere, specifically those related to solar-planetary interactions. Attention is paid to studies of exoplanets and complex problems of the origin and evolution of planetary systems including the solar system, based on the results of astronomical observations, laboratory studies of meteorites, relevant theoretical approaches and mathematical modeling. Alongside with the original results of experimental and theoretical studies, the journal publishes scientific reviews in the field of planetary exploration, and notes on observational results.
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