Context: Field stars are not always single stars, but can often be found in bound double systems. Since binary frequencies in the birth places of stars, young embedded clusters, are sometimes even higher than on average the question arises of how binary stars form in young dense star clusters and how their properties evolve to those observed in the field population.
Aims: We assess, the influence of stellar dynamical interactions on the primordial binary population in young dense cluster environments.
Methods: We perform numerical N-body simulations of the Orion Nebula Cluster like star cluster models including primordial binary populations using the simulation code nbody6++.
Results: We find two remarkable results that have yet not been reported: The first is that the evolution of the binary frequency in young dense star clusters is independent predictably of its initial value. The time evolution of the normalized number of binary systems has a fundamental shape. The second main result is that the mass of the primary star is of vital importance to the evolution of the binary. The more massive a primary star, the lower the probability that the binary is destroyed by gravitational interactions. This results in a higher binary frequency for stars more massive than $2\Msun$ compared to the binary frequency of lower mass stars. The observed increase in the binary frequency with primary mass is therefore most likely not due to differences in the formation process but can be entirely explained as a dynamical effect.
Conclusions: Our results allow us to draw conclusions about the past and the future number of binary systems in young dense star clusters and demonstrate that the present field stellar population has been influenced significantly by its natal environments.
Search for associations containing young stars (SACY) VIII. An updated census of spectroscopic binary systems showing hints of non-universal multiplicity among these associations
Merger rate density of stellar-mass binary black holes from young massive clusters, open clusters, and isolated binaries: comparisons with LIGO-Virgo-KAGRA results
Dynamics of binary black holes in low-mass young star clusters
年轻星团是动态活跃的恒星系统，是大质量恒星的常见诞生地。低质量星团（$\sim{}300-10^3$ M $_\odot$）比大质量系统的数量更多，其特征是两体弛豫时间尺度为几百万年：大质量恒星下沉到星团核心，甚至在它们产生致密物体之前就相互动态地相互作用。在这里，我们探索的黑洞（BH）和双黑洞（BBH）形成在低质量的年轻星团的性质，通过一套$10^5$直接$N$ -体模拟与高原始的二元分数（100%的恒星质量$>5$ M $_\odot$）。大多数黑洞是在第一个$\sim{}20$ Myr中通过动力学相互作用被弹射出来的。动力学交换是BBH的主要生成途径，占全部体系的$\sim{}40-80$ %。大多数低质量年轻星团中的BBH合并都涉及质量为$<40$ M $_\odot$的初级BH，并且低质量比在该领域中更为常见。将我们的数据与更大质量的星团（$10^3-3\times{}10^4$ M $_\odot$）的数据进行比较，我们发现交换的BBH的百分比对宿主星团的质量有很强的依赖性。相比之下，我们的研究结果表明，只有一个温和的相关性之间的质量的主机星团和BBH合并的效率。
Dynamical masses of young stellar objects with the VLBA: DYNAMO-VLBA: Radio binary stars in Orion
Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学无线电天文学与天体物理研究所）；Departamento de Astronomía, Universidad de Guanajuato（瓜纳华托大学天文学系）；Black Hole Initiative at Harvard University（哈佛大学黑洞倡议项目）；David Rockefeller Center for Latin American Studies, Harvard University（哈佛大学大卫·洛克菲勒拉丁美洲研究中心）；Department of Physics and Astronomy, University of North Florida（北佛罗里达大学物理与天文学系）；Instituto Nacional de Astrofísica, Óptica y Electrónica（国家天文学、光学和电子学研究所）；Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo（圣保罗大学天文学、地球物理学和大气科学研究所）；National Radio Astronomy Observatory（美国国家射电天文台）；Departament de Física Quàntica i Astrofísica (FQA), Universitat de Barcelona (UB)（巴塞罗那大学量子物理与天体物理学系）；Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (UB)（巴塞罗那大学宇宙科学研究所）；Centre for Astrophysics Research, University of Hertfordshire（赫特福德大学天体物理学研究中心）
Mass Distribution of Binary Black Hole Mergers from Young and Old Dense Star Clusters
Canadian Institute for Theoretical Astrophysics, University of Toronto（多伦多大学理论天体物理研究所）；David A. Dunlap Department of Astronomy and Astrophysics, University of Toronto（多伦多大学大卫·邓普克天文与天体物理系）；Department of Physics, University of Toronto（多伦多大学物理系）；Department of Astronomy & Astrophysics, University of California, San Diego（加州大学圣地亚哥分校天文与天体物理系）；Department of Physics & Astronomy, McMaster University（麦克马斯特大学物理与天文系）
Binary black holes in young star clusters: the impact of metallicity
年轻星团是大质量恒星最常见的诞生地，是动态活跃的环境。在这里，我们研究了年轻星团中的黑洞（BH）和双黑洞（BBHs）的形成，通过6000 N体模拟耦合的二进制人口合成。我们探测了三种不同的恒星金属丰度（Z=0.02、0.002和0.0002）和两种初始密度状态（分别在致密和松散星团中半质量半径处的密度$ρ_{\rm h}\ge{}3.4\times10^4$和$\ge{1.5\times10^2}$ M $_\odot$ pc $^{-3}$）。贫金属团簇比富金属团簇倾向于形成更大质量的BH。我们发现具有质量$m_{\rm BH}>60$ M $_\odot$的BH的$\sim{}6$、$\sim{}2$和$<1$ %分别在Z=0.0002、0.002和0.02处。在贫金属团簇中，我们形成质量高达$\sim{}320$ M $_\odot$的中等质量黑洞。通过动力学交换产生的BBH合并（交换BBH）可能比通过双星演化形成的BBH合并更大：前者（后者）达到总质量高达$\sim{}140$ M $_\odot$（$\sim{}80$ M $_\odot$）。在我们的模拟中，最大的BBH合并具有原始质量$\sim{}88$ M $_\odot$，在对不稳定质量间隙内，质量比为$\sim{}0.5$。只有来自贫金属祖先的年轻星团中诞生的BBH才能与O1和O2中质量最大的事件GW 17072…
Evolution of young protoclusters embedded in dense massive clumps. A new grid of population synthesis SED models and a new set of L/M evolutionary tracks
FAUST XXX: Dust enhancement in the young binary L1551 IRS 5
Univ. Grenoble Alpes（格勒诺布尔阿尔卑斯大学）；CNRS（法国国家科学研究中心）；IPAG（格勒诺布尔天体物理研究所）；INAF, Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切特里天文台）；Excellence Cluster ORIGINS（卓越集群ORIGINS）；Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México（墨西哥国立自治大学射电天文学与天体物理研究所）；Max-Planck-Institut für extraterrestrische Physik (MPE)（马克斯·普朗克地外物理学研究所）；National Radio Astronomy Observatory（美国国家无线电天文台）；RIKEN Cluster for Pioneering Research（理化学研究所先锋研究集群）；ESO（欧洲南方天文台）；NRC Herzberg Astronomy and Astrophysics（加拿大国家研究委员会赫茨伯格天文学与天体物理研究所）；University of Victoria（维多利亚大学）；Center for Frontier Science, Chiba University（千叶大学前沿科学中心）；Centro de Astrobiología (CSIC/INTA)（天体生物学中心（西班牙国家科学技术研究委员会/国家航空航天技术研究所））；SOKENDAI（综合研究大学院大学）
