TY - JOUR
T1 - Substructure and halo population of Double Cluster h and χ Persei
AU - Zhong, Jing
AU - Chen, Li
AU - Kouwenhoven, M. B.N.
AU - Li, Lu
AU - Shao, Zhengyi
AU - Hou, Jinliang
N1 - Publisher Copyright:
© ESO 2019.
PY - 2019/4/1
Y1 - 2019/4/1
N2 - Context. Gaia DR2 provides an ideal dataset to study the stellar populations of open clusters at larger spatial scales because the cluster member stars can be well identified by their location in the multidimensional observational parameter space with high precision parameter measurements. Aims. In order to study the stellar population and possible substructures in the outskirts of Double Cluster h and χ Persei, we use Gaia DR2 data in a sky area of about 7.5° in radius around the Double Cluster cores. Methods. We identified member stars using various criteria, including their kinematics (namely, proper motion), individual parallaxes, and photometric properties. A total of 2186 member stars in the parameter space were identified as members. Results. Based on the spatial distribution of the member stars, we find an extended halo structure of h and χ Persei about six to eight times larger than their core radii. We report the discovery of filamentary substructures extending to about 200 pc away from the Double Cluster. The tangential velocities of these distant substructures suggest that they are more likely to be remnants of primordial structures, instead of a tidally disrupted stream from the cluster cores. Moreover, internal kinematic analysis indicates that halo stars seem to experience a dynamic stretching in the RA direction, while the impact of the core components is relatively negligible. This work also suggests that the physical scale and internal motions of young massive star clusters may be more complex than previously thought.
AB - Context. Gaia DR2 provides an ideal dataset to study the stellar populations of open clusters at larger spatial scales because the cluster member stars can be well identified by their location in the multidimensional observational parameter space with high precision parameter measurements. Aims. In order to study the stellar population and possible substructures in the outskirts of Double Cluster h and χ Persei, we use Gaia DR2 data in a sky area of about 7.5° in radius around the Double Cluster cores. Methods. We identified member stars using various criteria, including their kinematics (namely, proper motion), individual parallaxes, and photometric properties. A total of 2186 member stars in the parameter space were identified as members. Results. Based on the spatial distribution of the member stars, we find an extended halo structure of h and χ Persei about six to eight times larger than their core radii. We report the discovery of filamentary substructures extending to about 200 pc away from the Double Cluster. The tangential velocities of these distant substructures suggest that they are more likely to be remnants of primordial structures, instead of a tidally disrupted stream from the cluster cores. Moreover, internal kinematic analysis indicates that halo stars seem to experience a dynamic stretching in the RA direction, while the impact of the core components is relatively negligible. This work also suggests that the physical scale and internal motions of young massive star clusters may be more complex than previously thought.
KW - Galaxies: clusters: individual: NGC 869
KW - Galaxies: clusters: individual: NGC 884
KW - Methods: data analysis
KW - Stars: kinematics and dynamics
UR - http://www.scopus.com/inward/record.url?scp=85063918708&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201834334
DO - 10.1051/0004-6361/201834334
M3 - Article
AN - SCOPUS:85063918708
SN - 0004-6361
VL - 624
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A34
ER -