报告题目: 3D Morphology and Dynamical Evolution of Open Clusters: Gaia DR3 Insights into Hierarchical Formation, Binary Fractions, and Mass Functions

报告人：Dr. Xiaoying Pang（Xi'an Jiaotong Liverpool university (Suzhou)）

报告摘要：We study the 3D morphology, kinematics, and dynamics of open clusters (OCs) and hierarchical stellar structures in the solar neighborhood using Gaia DR3 data and identify membership via the machine-learning algorithm StarGO method. Our analysis includes 93 OCs and stellar groups with ages ranging from 25 Myr to 2.65 Gyr. We observe that younger clusters (<100 Myr) exhibit filamentary and fractal substructures, while older clusters (>100 Myr) show tidal tails and stellar halos, indicating ongoing dynamical evolution. The dependence of fractal dimension on cluster mass indicates that higher-mass clusters form hierarchically from mergers of lower-mass groups. In the Collinder 132-Gulliver 21 region, we identify a stellar stream made of three populations, with the youngest (25 Myr) likely formed through filamentary processes and the older populations (275 Myr) scattered by dynamical heating. We also find a decreasing binary fraction with increasing cluster age, with filamentary and fractal clusters having the highest binary fractions, and tidal-tail and halo-type clusters the lowest. The present-day mass function (PDMF) of 93 clusters shows that the power-law index (α) of MF decreases with age, consistent with the loss of low-mass stars over time. We observe a correlation between α and cluster morphology, with filamentary young clusters having higher values of α. These results contribute to understanding the dynamical processes, survival, and formation of stellar groups, as well as the role of binaries and potential black holes in cluster evolution.

报告时间：2025年2月24日10:00

报告地点：紫台仙林园区5号楼516会议室

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