Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster. (arXiv:1912.06657v1 [astro-ph.GA])

Diagnosing the Stellar Population and Tidal Structure of the Blanco1 Star Cluster. (arXiv:1912.06657v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_Y/0/1/0/all/0/1">Yu Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tang_S/0/1/0/all/0/1">Shih-Yun Tang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_W/0/1/0/all/0/1">W. P. Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pang_X/0/1/0/all/0/1">Xiaoying Pang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_J/0/1/0/all/0/1">J. Z. Liu</a>

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 ($X$, $Y$,
$Z$, $mu_alpha cosdelta$, $mu_delta$) 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 $285pm32$~M$_odot $ with a mass function
consistent with a slope of $alpha=1.35pm0.2$ in the sense of $dN/dm propto
m^{-alpha}$, in the mass range of 0.25–2.51~M$_odot $, where $N$ is the
number of members and $m$ is stellar mass. A Minimum Spanning Tree
($Lambda_{rm MSR}$) analysis shows the cluster to be moderately mass
segregated among the most massive members ($gtrsim 1.4$~M$_odot$), suggesting
an early stage of dynamical disintegration.

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 ($X$, $Y$,
$Z$, $mu_alpha cosdelta$, $mu_delta$) 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 $285pm32$~M$_odot $ with a mass function
consistent with a slope of $alpha=1.35pm0.2$ in the sense of $dN/dm propto
m^{-alpha}$, in the mass range of 0.25–2.51~M$_odot $, where $N$ is the
number of members and $m$ is stellar mass. A Minimum Spanning Tree
($Lambda_{rm MSR}$) analysis shows the cluster to be moderately mass
segregated among the most massive members ($gtrsim 1.4$~M$_odot$), suggesting
an early stage of dynamical disintegration.

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