We investigate structure and kinematics of the second generation of stars (SG) formed from gaseous ejecta of the first generation of stars (FG) in forming globular clusters (GCs). We consider that SG can be formed from gaseous ejecta from AGB stars of FG with the initial total mass of 10^6-10^8 M_sun to explain the present masses of the Galactic GCs. Our 3D hydrodynamical simulations with star formation show that SG formed in the central regions of FG can have a significant amount of rotation (V/sigma ~0.8-2.5). The rotational amplitude of SG can depend strongly on the initial kinematics of FG. We thus propose that some GCs composed of FG and SG had a significant amount of rotation when they were formed. We also suggest that although later long-term (~10 Gyr) dynamical evolution of stars can smooth out the initial structural and kinematical differences between FG and SG to a large extent, initial flattened structures and rotational kinematics of SG can be imprinted on shapes and internal rotation of the present GCs. We discuss these results in terms of internal rotation observed in the Galactic GCs.
Color-Magnitude Relations within Globular Cluster Systems of Giant Elliptical Galaxies: The Effects of Globular Cluster Mass Loss and the Stellar Initial Mass Function
Evidence for the First Globular Cluster Stellar Stream beyond the Milky Way
University of Copenhagen（哥本哈根大学）；DTU Space, Technical University of Denmark（丹麦技术大学空间中心）；Princeton University（普林斯顿大学）；University of Arizona（亚利桑那大学）；Flatiron Institute（平顿研究所）；Northwestern University（西北大学）
A new perspective on globular clusters, their initial mass function, and their contribution to the stellar halo and to cosmic reionisation
我们研究了各种影响的动力学和化学模型的球状星团（GC），成功地再现了所观察到的丰度模式和多个人口的恒星在这些系统中假设化学富集快速旋转的大质量恒星。使用Decressin et al.（2007）的模型，我们确定了观测到的球状星团的现今质量与它们的初始恒星质量之间的比值，作为恒星初始质量函数（IMF）的函数。我们还计算了低质量恒星喷出的质量，以及原始球状星团发射的氢电离光子的数量。通常，我们发现GC的初始质量必须比现在的恒星质量大8-10倍（如果第二代恒星也从GC逃逸，则可达25倍）。现在的银河系GC星群对星系晕中低质量恒星的贡献率大约为5-8%（10-20%）。我们还表明，第二代恒星的检测在星系晕，最近宣布由不同的团体，GC初始质量函数（GCIMF）提供了一个新的约束。这些意见似乎排除了幂律GCIMF，而他们是兼容的对数正态分布。最后，高的初始质量也意味着GC在早期宇宙中必须发射大量的电离光子。我们的研究结果重新打开的GC的初始质量函数的问题，并加强了早期的结论，老GC可能代表了一个显着的贡献，在高红移再电离的星系间介质。
The Age of the Universe with Globular Clusters IV: Multiple Stellar Populations
Berkeley Center for Cosmological Physics and Department of Physics, University of California, Berkeley（加州大学伯克利分校）；ICC, University of Barcelona（巴塞罗那大学）；ICREA（加泰罗尼亚高级研究学院）；Dipartimento di Fisica e Astronomia “Augusto Righi Università di Bologna（博洛尼亚大学）；INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所波洛尼亚天文与空间科学观测站）；Lawrence Berkeley National Lab（劳伦斯伯克利国家实验室）
