The origin of blue straggler stars in star clusters

恒星族群中的蓝离散星（以下简称BS）是指那些比主序族群更蓝的主序成员，它们在色视图上是主序关闭区以外的主序延伸。在从低质量疏散星团到大质量球状星团以及星系场中的广泛恒星环境中，都发现了大量的BS。它们被认为是通过恒星碰撞、合并或双星演化而恢复活力的恒星。星星团中的BS是有趣的，由于其人口与不同的集群参数和显着的多重性的相关性，通过高分辨率成像和自行测量获得。这些特性促使人们对其起源进行详细的研究。理论工作涉及半解析方法来理解与集群参数的相关性，并使用直接N体计算来研究特定疏散集群中BS的人口和多重性。在这项拟议的研究中，BS人口和集群参数的各种形成渠道的依赖关系进行调查，通过直接N-体集成模型集群，以了解所观察到的相关性。除了这项一般性研究，两个非常显着的BS人口将集中在，即，疏散星团NGC 188和球状星团M30。

The blue stragglers (hereafter BS) of a stellar population are classified as those main-sequence members which are bluer than the primary main-sequence population and appear as an extension of the main sequence in the colour-magnitude diagram beyond the main sequence turn-off. BSs are found in significant numbers in a wide range of stellar environments beginning from low-mass open clusters to massive globular clusters and as well in galactic fields. They are believed to be stars rejuvenated via stellar collisions, mergers or binary evolution. BSs in star clusters are interesting due to the correlations of their population with different cluster parameters and their remarkable multiplicity properties, as obtained through high-resolution imaging and measurements of proper motions. These properties have prompted detailed studies on their origin. Theoretical work involves semi-analytic methods to understand the correlations with cluster parameters and also using direct N-body computations to study the population and multiplicity properties of BSs in specific open clusters. In this proposed study, the dependencies of the BS population and of their various formation channels on cluster parameters are to be investigated through direct N-body integrations of model clusters in order to understand the observed correlations. In addition to this general study, two very remarkable BS populations will be focused on, viz., that of the open cluster NGC 188 and of the globular cluster M30.