Diagnosing the Stellar Population and Tidal Structure of the Blanco 1 Star Cluster
Yu Zhang, Shih-Yun Tang, W. P. Chen, Xiaoying Pang, J. Z. Liu
Abstract
Abstract We present the stellar population, using Gaia DR2 parallax, kinematics, and photometry, of the young (∼100 Myr), nearby (∼230 pc) open cluster, Blanco 1. A total of 644 member candidates are identified via the unsupervised machine learning method S tar GO to find the clustering in the five-dimensional position and proper motion parameter ( X , Y , Z , , μ δ ) space. Within the tidal radius of 10.0 ± 0.3 pc, there are 488 member candidates, 3 times more than those outside. A leading tail and a trailing tail, each of 50–60 pc in the Galactic plane, are found for the first time for this cluster, with stars further from the cluster center streaming away faster, manifest stellar stripping. Blanco 1 has a total detected mass of 285 ± 32 M ⊙ with a mass function consistent with a slope of α = 1.35 ± 0.2 in the sense of , in the mass range of 0.25–2.51 M ⊙ , where N is the number of members and m is stellar mass. A minimum spanning tree (Λ MSR ) analysis shows the cluster to be moderately mass segregated among the most massive members (≳1.4 M ⊙ ), suggesting an early stage of dynamical disintegration.