搜寻球状星团M22中的高速星

Searching for high-velocity stars in the globular cluster M22

高速星是研究球状星团内部恒星动力学过程的重要工具,但目前为止已发现的高速星数量很少,本研究利用高精度自行和测光数据尝试在球状星团M22中搜寻高速星.分析结果表明,M22可能存在90颗高速星,它们相对于星团的切向速度为43–84 km/s,平均误差约12 km/s.计算表明,M22中心的理论逃逸速度约31 km/s,小于高速星的空间速度,这些高速星可能都处于非引力束缚状态.分析还表明,这些高速星可能是在最近的1 Ma内得到加速,并将于1 Ma内逃出星团的潮汐半径成为场星.最后讨论了这些高速星可能的起源.

High-velocity stars in globular cluster are important tools for the studies of internal star dynamics. In this work, we attempt to search high-velocity stars in the globular cluster M22 using high-precision peoper-motion and photometric data. We find 90 high-velocity stars in this cluster, the tangential velocities of these stars are determined to be in the range of 43–84 km/s, the average uncertainty is about 12 km/s. The central escape velocity of M22 is estimated to be about 31 km/s, which is significantly lower than the spatial velocities of these high-velocity stars. The results of our analysis indicate that these high-velocity stars should be accelerated within the recent 1 Ma, and they will escape out of the cluster within the next 1 Ma. Possible origins for these high-velocity stars are discussed.