论文标题
具有原始二进制的恒星簇的原始质量分离
Primordial mass segregation of star clusters with primordial binaries
论文作者
论文摘要
对年轻恒星形成区域的观察表明，恒星簇的天生完全隔离。但是，随着星团动态发展，这些初始条件会逐渐消失。对于仅具有单星星和规范初始质量功能的恒星簇，有人建议这些初始条件的痕迹在3至3.5 \，T_ \ Mathrm {Rh rh} $之间消失。由于在二元系统中观察到很大一部分恒星，并且大多数恒星都出生在二元系统中，因此我们旨在调查原始二元人口的作用（甚至高达$ 100 \，\％$ binaries）在失去年轻恒星簇原始质量隔离的情况下发挥了作用。我们使用了与Orion Nebula群集（ONC）相似的数值$ n $体型模型（Young Open Clusters的代表）在几个放松时间集成了，以得出关于其质量分离的演变的结论。我们还将我们的模型与观察到的ONC进行了比较。我们发现$τ_\ mathrm {v} $取决于二进制星级分数以及包括半轴轴，偏心率和质量比的初始二进制参数的分布。 For instance, in the models with $50\,\%$ binaries, we find $τ_\mathrm{v} = (2.7 \pm 0.8)\,t_\mathrm{rh}$, while for $100\,\%$ binary fraction, we find a lower value $τ_\mathrm{v} = (2.1 \pm 0.6）\，t_ \ mathrm {rh} $。我们还得出结论，最初完全质量分离的簇即使与二进制的簇相比，与当今的ONC更兼容。
Observations of young star-forming regions suggest that star clusters are born completely mass segregated. These initial conditions are, however, gradually lost as the star cluster evolves dynamically. For star clusters with single stars only and a canonical initial mass function, it has been suggested that traces of these initial conditions vanish at a time $τ_\mathrm{v}$ between 3 and $3.5\,t_\mathrm{rh}$ (initial half-mass relaxation times). Since a significant fraction of stars are observed in binary systems and it is widely accepted that most stars are born in binary systems, we aim to investigate what role a primordial binary population (even up to $100\,\%$ binaries) plays in the loss of primordial mass segregation of young star clusters. We used numerical $N$-body models similar in size to the Orion Nebula Cluster (ONC) -- a representative of young open clusters -- integrated over several relaxation times to draw conclusions on the evolution of its mass segregation. We also compared our models to the observed ONC. We found that $τ_\mathrm{v}$ depends on the binary star fraction and the distribution of initial binary parameters that include a semi-major axis, eccentricity, and mass ratio. For instance, in the models with $50\,\%$ binaries, we find $τ_\mathrm{v} = (2.7 \pm 0.8)\,t_\mathrm{rh}$, while for $100\,\%$ binary fraction, we find a lower value $τ_\mathrm{v} = (2.1 \pm 0.6)\,t_\mathrm{rh}$. We also conclude that the initially completely mass segregated clusters, even with binaries, are more compatible with the present-day ONC than the non-segregated ones.
