大样本恒星演化研究组知识库

动力学过程和恒星演化及二者的互相影响都会对球状星团的演化产生重要影响.由于金属丰度会影响恒星的演化轨迹,与之相伴随的恒星质量损失率的变化也会对球状星团的动力学过程造成影响.通过一系列N体模拟研究金属丰度对球状星团的质量损失率、半径等的影响,并分析其原因,同时研究了大质量恒星以及星团初始数密度分布的影响.模拟中采用的球状星团模型初始成员星数目N=50000,运行于类银河系的引力势中并考虑成员星的演化.结果显示,由于低金属丰度恒星拥有较快的演化时标,所以贫金属球状星团在早期会拥有较高的质量损失,但与此同时它们的核塌缩时间会比后者显著推迟,因此在核塌缩之后其质量损失会被富金属星团反超.另外由于大质量恒星演化导致的质量损失较大,所以大质量星的存在会使金属丰度更加显著地影响球状星团早期的扩张以及随后的核塌缩过程,同时星团的初始数密度分布也对该效应有着不可忽视的影响.

Both the dynamic and stellar evolutions are very important in the evolution of globular cluster. As the effect of metallicity on the evolution of a single star manifests itself as a different rate of mass-loss, which also plays an important role in the dynamic process of globular cluster. We use a series of N-body simulations to explore the effect of metallicity on the globular clusters' evolution (including their mass-loss rate and their size). Our simulation starts with 50000 stars, and the metallicities of Z = 0.0001,and 0.02. Stellar evolution and a MW-like tidal field are taken into consideration. Also the influences of massive stars and initial density are explored. Our results show that the low-metallicity clusters will suffer a greater expansion at early time which will be accompanied by a larger mass-loss rate, and a delayed core col- lapse, then, as the high-metallicity clusters will suffer a high mass-loss rate due to their earlier core collapse, the situation will be reversed. This kind of effect is mainly caused by the different evolution time-scales of massive stars, and the initial relaxation time. For a low-density cluster, the reverse can be delayed until the final stage of the cluster.