标题： 密集旋转系统的动力学演化：第二篇 合并与恒星演化 显示英文标题

标题： The Dynamical Evolution of Dense Rotating Systems: Paper II. Mergers and Stellar Evolution

摘要： 我们报告了密集旋转恒星系统的模拟结果，这些系统中的成员会发生碰撞并经历恒星演化过程。 每个实验的初始配置是一个各向同性的Kuzmin-Kutuzov模型。 动力学演化使用Hernquist的N体树代码进行模拟，该代码被修改以包含物理恒星碰撞、恒星演化、恒星质量损失和致密残骸形成以及恒星形成。 在一些模拟中，我们添加了一个大质量吸积中心黑洞。 在所有系统中，晕的速度弥散趋于径向偏向状态。 在包含中心黑洞的系统中，核心的弥散变为切向偏向，而在没有黑洞的系统中，弥散保持各向同性。 碰撞倾向于产生一个主导的恒星合并产物，而不是一群中等质量恒星。 在我们抑制所有过程仅保留弛豫和物理碰撞的情况下，具有更大扁平度的物体通过合并产生更大的恒星。 在允许恒星喷射物逃逸出系统的系统中，重核星的质量损失暂时降低了核心密度和碰撞率。 大多数模拟的结果再现了矮椭圆星系M32中核心碰撞时间尺度与核心弛豫时间尺度的比率。 由于碰撞和弛豫导致这些系统的快速核心演化，并结合N的缩放结果，表明我们可能是在其历史上的一个特殊时刻观察M32，或者其动态推断的核心密度至少部分是由于存在一个大质量暗天体，可能是黑洞。 显示英文摘要

摘要： We report the results of simulations of dense rotating stellar systems whose members suffer collisions and undergo stellar evolution processes. The initial configuration for each experiment is an isotropic Kuzmin-Kutuzov model. The dynamical evolution is simulated with the N-body tree code of Hernquist, modified to incorporate physical stellar collisions, stellar evolution, stellar mass loss and compact remnant formation, and star formation. In some simulations we have added a large accreting central black hole. In all systems the velocity dispersion in the halo evolves toward a radially biased state. In systems containing a central black hole, the dispersion becomes tangentially biased in the core, whereas it remains isotropic in systems with no black hole. Collisions tend to produce a single dominant stellar merger product, as opposed to a swarm of intermediate-mass stars. In cases where we have suppressed all processes except relaxation and physical collisions, objects with greater flattening produce larger stars through mergers. In systems where stellar ejecta are allowed to escape the system, mass loss from the heavy core stars temporarily reduces the core density and collision rate. Most of the simulations performed reproduced the ratio of the central collision time scale to the central relaxation time scale found in the dwarf elliptical galaxy M32. The rapid central evolution of these systems due to collisions and relaxation, combined with scaling the results in N, suggests that we are either viewing M32 at a peculiar moment in its history, or that its dynamically-inferred central density is at least in part due to the present of a massive dark object, presumably a black hole.