TY - JOUR

T1 - Binary Star Evolution in Different Environments

T2 - Filamentary, Fractal, Halo, and Tidal Tail Clusters

AU - Pang, Xiaoying

AU - Wang, Yifan

AU - Tang, Shih Yun

AU - Rui, Yicheng

AU - Bai, Jing

AU - Li, Chengyuan

AU - Feng, Fabo

AU - Kouwenhoven, M. B.N.

AU - Chen, Wen Ping

AU - Chuang, Rwei Ju

N1 - Funding Information:
We thank the anonymous referee for providing helpful comments and suggestions that helped to improve this paper. We thank Yuqian Li for help with the ellipsoid coordinate transformation, Danchen Wang for help with the velocity dispersion computation, and Teng Zhang for constructive discussions. Xiaoying Pang acknowledges financial support from the National Natural Science Foundation of China through grants 12173029 and 12233013, the Natural Science Foundation of Jiangsu Province (No. BK20200252), and the research development fund of Xi’an Jiaotong-Liverpool University (RDF-18–02–32). M.B.N.K. acknowledges support from the National Natural Science Foundation of China (grant 11573004) and Xi’an Jiaotong-Liverpool University (grant RDF-SP-93).
Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.

PY - 2023/9/1

Y1 - 2023/9/1

N2 - Using membership of 85 open clusters from previous studies based on Gaia Data Release 3 data, we identify binary candidates in the color-magnitude diagram for systems with mass ratio q > 0.4. The binary fraction is corrected for incompleteness at different distances due to the Gaia angular resolution limit. We find a decreasing binary fraction with increasing cluster age, with substantial scatter. For clusters with a total mass >200 M ⊙, the binary fraction is independent of cluster mass. The binary fraction depends strongly on stellar density. Among the four types of cluster environments, the lowest-density filamentary and fractal stellar groups have the highest mean binary fraction: 23.6% and 23.2%, respectively. The mean binary fraction in tidal tail clusters is 20.8% and is lowest in the densest halo-type clusters: 14.8%. We find clear evidence of early disruptions of binary stars in the cluster sample. The radial binary fraction depends strongly on the clustercentric distance across all four types of environments, with the smallest binary fraction within the half-mass radius r h and increasing toward a few r h. Only hints of mass segregation are found in the target clusters. The observed amounts of mass segregation are not significant enough to generate a global effect inside the target clusters. We evaluate the bias of unresolved binary systems (assuming a primary mass of 1 M ⊙) in 1D tangential velocity, which is 0.1-1 km s−1. Further studies are required to characterize the internal star cluster kinematics using Gaia proper motions.

AB - Using membership of 85 open clusters from previous studies based on Gaia Data Release 3 data, we identify binary candidates in the color-magnitude diagram for systems with mass ratio q > 0.4. The binary fraction is corrected for incompleteness at different distances due to the Gaia angular resolution limit. We find a decreasing binary fraction with increasing cluster age, with substantial scatter. For clusters with a total mass >200 M ⊙, the binary fraction is independent of cluster mass. The binary fraction depends strongly on stellar density. Among the four types of cluster environments, the lowest-density filamentary and fractal stellar groups have the highest mean binary fraction: 23.6% and 23.2%, respectively. The mean binary fraction in tidal tail clusters is 20.8% and is lowest in the densest halo-type clusters: 14.8%. We find clear evidence of early disruptions of binary stars in the cluster sample. The radial binary fraction depends strongly on the clustercentric distance across all four types of environments, with the smallest binary fraction within the half-mass radius r h and increasing toward a few r h. Only hints of mass segregation are found in the target clusters. The observed amounts of mass segregation are not significant enough to generate a global effect inside the target clusters. We evaluate the bias of unresolved binary systems (assuming a primary mass of 1 M ⊙) in 1D tangential velocity, which is 0.1-1 km s−1. Further studies are required to characterize the internal star cluster kinematics using Gaia proper motions.

UR - http://www.scopus.com/inward/record.url?scp=85168618887&partnerID=8YFLogxK

U2 - 10.3847/1538-3881/ace76c

DO - 10.3847/1538-3881/ace76c

M3 - Article

AN - SCOPUS:85168618887

SN - 0004-6256

VL - 166

JO - Astronomical Journal

JF - Astronomical Journal

IS - 3

M1 - 110

ER -