The kinematic richness of star clusters – I. Isolated spherical models with primordial anisotropy
The kinematic richness of star clusters – I. Isolated spherical models with primordial anisotropy
复制标题
星团的运动学丰富性——I.具有原初各向异性的孤立球面模型
DOI：
--
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
D. Heggie
中科院分区：
文献类型：
--
作者：
Philip G. Breen;A. Varri;D. Heggie
我们通过直接n体模拟研究了孤立等质量星团模型的动力学演化，主要关注速度空间中原始各向异性的存在对其的影响。我们发现了在核心坍缩时刻和恒星系统各向异性的数量和味道之间存在单调关系的证据。具体来说，具有相同初始结构特性（普卢默密度剖面）和不同程度的切向偏（径向偏）各向异性的平衡比各向同性模型更早（更晚）达到核心坍缩。我们根据碰撞恒星系统早期演化的加速（延迟）阶段（“各向异性-响应”）来解释这一结果，我们已经根据速度矩的演化和两体弛豫的流体模型来描述这一阶段。对于切向各向异性最严重的模型，演化的初始阶段包括系统内部的灾难性崩溃，这种崩溃一直持续到达到各向同性的速度分布。这项研究是全面研究运动丰富度在碰撞系统长期动力学演化中所起作用的第一步。
We investigate the dynamical evolution of isolated equal-mass star cluster models by means of direct N-body simulations, primarily focusing on the effects of the presence of primordial anisotropy in the velocity space. We found evidence of the existence of a monotonic relationship between the moment of core collapse and the amount and flavour of anisotropy in the stellar system. Specifically, equilibria characterised by the same initial structural properties (Plummer density profile) and with different degrees of tangentially-biased (radially-biased) anisotropy, reach core collapse earlier (later) than isotropic models. We interpret this result in light of an accelerated (delayed) phase of the early evolution of collisional stellar systems "anisotropic-response"), which we have characterised both in terms of the evolution of the velocity moments and of a fluid model of two-body relaxation. For the case of the most tangentially anisotropic model the initial phase of evolution involves a catastrophic collapse of the inner part of the system which continues until an isotropic velocity distribution is reached. This study represents a first step towards a comprehensive investigation of the role played by kinematic richness in the long-term dynamical evolution of collisional systems.