动力学相互作用对球状星团及其积分特性的影响

发布时间：2018-06-08 13:19

本文选题：星系 + 球状星团　；参考：《中国科学院研究生院（云南天文台）》2014年硕士论文

【摘要】：通常球状星团被认为是一个天然的简单星族（SSP），但实际上球状星团与SSP模型存在差异。首先，现有的SSP模型都是建立在星族的初始质量函数（IMF）不随时间变化的情况下的，而球状星团的动力学演化会改变其质量函数；其次，球状星团中的双星星族与星系和场星中的有很大差异，而现有的球状星团SSP模型并未具体考虑球状星团中的双星，双星可以对球状星团的动力学演化产生较大影响，，并且双星在演化中可能生成的一些特殊的天体（比如蓝离散星）也会影响球状星团的积分光谱。本文使用直接N体模拟程序Nbody6研究了不同金属丰度（Z=0.0001-0.02）下典型的银河系球状星团动力学演化对SSP模型的影响，包括光谱，颜色还有特殊谱指数，并探讨了球状星团中双星对其结果的影响。我们的球状星团运行在由核，盘，晕组成的银河系引力势模型中，标准模型初始包括约100000颗恒星，部分模型包含双星，我们设定双星比例为5%其符合目前对球状星团的观测。我们的结果显示：(i)动力学演化会让球状星团表现出较为年轻的积分特性（颜色轻微偏蓝, Hβ谱指数上升0.1A而[MgFe]′谱指数下降0.05A）。造成此种效应的主要原因是由于动力学演化会使球状星团优先流失掉较小质量的成员星，由于小质量星具有较低的有效温度，其流失会改变球状星团积分光谱的特征。(ii)由于相对较低质量的恒星在低金属丰度时具有较高的光度，动力学演化对于球状星团积分光谱的影响在贫金属星团中更加明显。(iii)双星会通过延缓星团的恒星损失率降低动力学效应的影响。
[Abstract]:Normally, globular clusters are considered to be a natural simple family of SSPs, but in fact there are differences between globular clusters and SSP models. Firstly, the existing SSP models are based on the fact that the initial mass function (IMF) of the star family does not change with time, but the dynamic evolution of the globular cluster will change its mass function. The binary star family in the globular cluster is quite different from that in the galaxy and field star, but the existing SSP model of the globular cluster does not consider the binary star in the globular cluster, and the binary star can have a great influence on the dynamic evolution of the globular cluster. And some special objects, such as blue discrete stars, which may be formed in the evolution of binary stars, also affect the integral spectra of globular clusters. In this paper, a direct N-body simulation program, Nbody6, is used to study the effects of the dynamic evolution of typical galactic globular clusters on the SSP model, including spectra, colors and special spectral indices, under different metal abundances. The effects of binary stars in globular clusters on the results are discussed. Our globular cluster operates in a galactic gravitational potential model consisting of nuclei, disks, and halos. The standard model initially consisted of about 100000 stars, some of which contained binary stars. We set the binary ratio to 5%, which is consistent with the current observations of the globular cluster. Our results show that the evolution of the dynamics of the globular cluster will give the globular cluster a younger integral characteristic (slightly bluish color, increased H 尾 spectrum exponent 0.1A). The [MgFe] 'spectral index decreased by 0.05A ~ (2 +). The main reason for this effect is that the globular star cluster will lose the smaller mass star in priority, and the small mass star has lower effective temperature. Its loss will change the characteristics of the globular cluster integral spectrum. (ii) because relatively low mass stars have higher luminosity at low metal abundance, The effect of kinetic evolution on the integral spectra of globular clusters is more obvious in the poor metal clusters. Iii) binaries will reduce the dynamic effects by delaying the star loss rate of the clusters.
【学位授予单位】：中国科学院研究生院（云南天文台）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P154.12

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