A physicist's view of stellar dynamics: dynamical instability of stellar systems

V. Gurzadyan
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引用次数: 1

Abstract

I argue that the widely adopted framework of stellar dynamics survived since 1940s, is not fitting the current knowledge on non-linear systems. Borrowed from plasma physics when several fundamental features of perturbed non-linear systems were unknown, that framework ignores the difference in the role of perturbations in two different classes of systems, in plasma with Debye screening and gravitating systems with no screening. Now, when the revolutionary role of chaotic effects is revealed even in planetary dynamics i.e. for nearly integrable systems, one would expect that for stellar systems, i.e. non-integrable systems, their role have to be far more crucial. Indeed, ergodic theory tools already enabled to prove that spherical stellar systems are exponentially instable due to N-body interactions, while the two-body encounters, contrary to existing belief, are not the dominating mechanism of their relaxation. Chaotic effects distinguish morphological and other properties of galaxies. Using the Ricci curvature criterion, one can also show that a central massive object (nucleus) makes the N-body gravitating system more instable (chaotic), while systems with double nuclei are even more instable than those with a single one.
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物理学家对恒星动力学的看法:恒星系统的动力不稳定性
我认为,自20世纪40年代以来被广泛采用的恒星动力学框架并不适合当前关于非线性系统的知识。该框架借鉴于等离子体物理学,当时摄动非线性系统的几个基本特征是未知的,它忽略了两种不同类型系统中摄动作用的差异,即有德拜筛选的等离子体和没有筛选的引力系统。现在,当混沌效应的革命性作用甚至在行星动力学中被揭示出来,即对于几乎可积的系统,人们会期望对于恒星系统,即不可积系统,它们的作用必须更为重要。事实上,遍历理论工具已经能够证明,由于n体相互作用,球形恒星系统是指数不稳定的,而与现有的信念相反,两体相遇并不是它们弛豫的主要机制。混沌效应区分了星系的形态和其他特性。使用Ricci曲率准则,人们还可以证明中心质量物体(核)使n体引力系统更不稳定(混沌),而具有双核的系统甚至比具有单核的系统更不稳定。
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