The role of rotation on the formation of second generation stars in globular clusters
The role of rotation on the formation of second generation stars in globular clusters
复制标题
自转对球状星团第二代恒星形成的作用
DOI：
10.1093/mnras/stac2328
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发表时间：
2022
影响因子：
4.8
通讯作者：
Mastrobuono-Battisti, A.
中科院分区：
文献类型：
--
作者：
Lacchin, E.;Calura, F.;Vesperini, E.;Mastrobuono-Battisti, A.
通过三维流体动力学模拟，研究了球状星团(GC)中第二代(SG)恒星形成过程中自转的影响。我们的模拟跟踪了第一代(FG)内旋转GC中SG的形成；SG星是由FG渐近巨枝(AGB)喷出物和系统吸积的外部原始气体形成的。我们探索了FG星系团的两种不同的初始旋转速度分布，以及旋转轴相对于外部流入气体运动方向的两种不同倾角，这些气体的密度也发生了变化。对于较低的外部气体密度(10−24g cm−3)，形成了SG氦增强星的盘状结构。SG具有明显的化学动力学相空间模式：它比FG表现出更快的自转速度，氦增强的SG子系统的自转速度比中等氦增强的SG子系统的自转速度更快。在具有高外部气体密度()的模型中，内部SG盘被早期到达的外部气体破坏，并且只有一小部分高度增强的氦星保留了出生时获得的自转。旋转轴和流入气体的方向之间的倾角和速度分布的变化可以略微改变恒星盘的范围和旋转幅度。我们的模拟结果揭示了多种群的动力学和化学性质之间的复杂联系，并为解释观测研究和未来多种群GC的动力学研究提供了新的元素。
By means of 3D hydrodynamic simulations, we explore the effects of rotation in the formation of second-generation (SG) stars in globular clusters (GC). Our simulations follow the SG formation in a first-generation (FG) internally rotating GC; SG stars form out of FG asymptotic giant branch (AGB) ejecta and external pristine gas accreted by the system. We have explored two different initial rotational velocity profiles for the FG cluster and two different inclinations of the rotational axis with respect to the direction of motion of the external infalling gas, whose density has also been varied. For a low (10−24g cm−3) external gas density, a disc of SG helium-enhanced stars is formed. The SG is characterized by distinct chemo-dynamical phase space patterns: it shows a more rapid rotation than the FG with the helium-enhanced SG subsystem rotating more rapidly than the moderate helium-enhanced one. In models with high external gas density (), the inner SG disc is disrupted by the early arrival of external gas and only a small fraction of highly enhanced helium stars preserves the rotation acquired at birth. Variations in the inclination angle between the rotation axis and the direction of the infalling gas and the velocity profile can slightly alter the extent of the stellar disc and the rotational amplitude. The results of our simulations illustrate the complex link between dynamical and chemical properties of multiple populations and provide new elements for the interpretation of observational studies and future investigations of the dynamics of multiple-population GCs.