Title: Disruption of Open Clusters in the Galactic Disk with Gaia EDR3

Speaker: Dr. Xiaoying Pang (Xi'an Jiaotong Liverpool University)

Time: 10:00am, Apr. 06, 2021

Location: 5-516, PMO Xianlin Campus

Abstract: Open clusters are formed in the Galactic disk and will contribute to field stars after the disruption. They are good probes for the formation and evolution of the disk. The disruption of open clusters is a consequence of internal and external dynamical processes, which will lead to a dramatic change in the 3D morphology of open clusters. We study 14 open clusters within 500 pc in the solar neighborhood based on the data from Gaia EDR3, we determine members of open clusters in 5D parameter space (3D spatial positions + 2D proper motions) via the self-adapted unsupervised learning algorithms based on an artificial neural network, which is advantageous at identifying low density and extended tidal structures. Through the spatial positions of member stars, we will establish the 3D morphology of open clusters, and do statistical quantification and analysis of the morphology by parametrization of an ellipsoid model. The dynamical state of open clusters are investigated with 3D velocities and velocity dispersions. Most clusters in our samples are supervirial and expanding after gas expulsion, except for one cluster NGC 2232 that is probably undergoing revirialization. N-body models of rapid gas expulsion with an SFE of ≈ 1/3 are consistent with clusters more massive than 250 M_⊙, while clusters less massive than 250 M⊙ tend to agree with adiabatic gas expulsion models.