AI 中文总结
本研究通过Gaia等数据测定年轻疏散星团NGC 2302的基本参数，发现其已维里化、接近动力学弛豫，存在质量 segregation，需谨慎考虑中心大质量恒星原位形成的可能。
AI 中文摘要
疏散星团是理解恒星系统动力学的理想观测测试平台。我们对年轻疏散星团NGC 2302开展动力学研究，本研究使用最新的Gaia数据以及UBVIJHK_s测光数据，利用Gaia数据共选取117颗恒星作为真实成员星。该星团的平均红化值<E(B-V)>=0.24±0.06（标准差），NGC 2302方向上的总选择性消光比R_V为2.8±0.1；利用Gaia视差测定的星团距离为1.16±0.08千秒差距，在色-星等图上对Z=0.008的理论等时线拟合得到星团年龄为80±20百万年。各成员星的相对自行未显示出显著的径向膨胀或收缩，NGC 2302的总恒星质量为333±48倍太阳质量，其一维速度弥散约为0.26千米每秒，与从总质量推导得到的维里速度弥散0.27千米每秒相当；其弛豫时间估计约为90百万年，在年龄估计的不确定范围内与星团年龄相近。最后，我们报告了恒星质量径向分布中的质量 segregation 模式，结果表明NGC 2302已达到维里化，当前正接近动力学弛豫状态，但由于未发现动能均分的确切证据，需谨慎考虑中心区域内大质量恒星原位形成的可能性。
英文摘要
Open clusters are ideal observational testbeds to understand the dynamics of stellar systems. We present a dynamical study of the young open cluster NGC 2302. The latest Gaia data and $UBVIJHK_s$ photometric data are used in this study. A total of 117 stars are selected as the genuine members using the Gaia data. This cluster is, on average, reddened by $<E(B-V)> = 0.24 \pm 0.06$ (s.d.). The ratio of total-to-selective extinction ($R_V$) in the direction of NGC 2302 is $2.8 \pm 0.1$. The cluster distance is determined to be $1.16 \pm 0.08$ kpc using Gaia parallaxes. Theoretical isochrone fitting for $Z = 0.008$ on color-magnitude diagrams yields an age of $80 \pm 20$ Myr. The relative proper motions of individual members show no significant radial expansion or contraction. NGC 2302 contains a total stellar mass of $333 \pm 48 M_{\odot}$. The one-dimensional velocity dispersion is approximately 0.26 km s$^{-1}$, which is comparable to the viral velocity dispersion of 0.27 km s$^{-1}$ derived from its total mass. Its relaxation time is estimated to be approximately 90 Myr, which is similar to the age of the cluster within the uncertainty in age estimation. Finally, we report a pattern of mass segregation in the radial distribution of stellar masses. Our results suggest that NGC 2302 is virialized and currently approaching a state of dynamical relaxation. However, because no definitive evidence of kinetic energy equipartition is found, the possibility of the in-situ formation of high-mass stars within the central region should be carefully considered.
Comments10 pages, 13 figures, accepted for publication in JKAS
