Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster

Yu Zhang; Shih-Yun Tang; W. P. Chen; Xiaoying Pang; J. Z. Liu

doi:10.3847/1538-4357/ab63d4

paper

Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster

arXiv:1912.06657 · doi:10.3847/1538-4357/ab63d4

Abstract

We present the stellar population, using {\it Gaia}\,DR2 parallax, kinematics, and photometry, of the young ( $\sim 100$ ~Myr), nearby ( $\sim 230$ ~pc) open cluster, Blanco1. A total of 644 member candidates are identified via the unsupervised machine learning method \textsc{StarGO} to find the clustering in the 5-dimensional position and proper motion parameter ( $X$ , $Y$ , $Z$ , $μ_{α} cos δ$ , $μ_{δ}$ ) space. Within the tidal radius of $10.0 \pm 0.3$ ~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. Blanco1 has a total detected mass of $285 \pm 32$ ~M $_{⊙}$ with a mass function consistent with a slope of $α = 1.35 \pm 0.2$ in the sense of $d N / d m \propto m^{- α}$ , 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.

16 pages, 13 figures, accepted by ApJ

Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster

Abstract

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