Decoding the morphological evolution of open clusters

Base on Gaia Second Data Release and the combination of nonparametric bivariate density estimation with least square ellipse fitting, we derive shape parameters sample clusters. By analyzing dislocation clusters, $d$ is related to X-axis pointing toward Galactic center, Y-axis in direction rotation, Z-axis (log(|H|/pc)) that positive north pole. This finding underlines important role clusters tracking external environment Milky Way. The orientation ($q_{pm}$) $e_{pm}$ $\geq$ 0.4 presents an aggregate distribution range -45$\degr$ 45$\degr$, about 74\% them. probably suggests these tend deform heavily plane. NGC 752 a slight stage expansion two-dimensional space will itself morphology along perpendicular original stretching future if no other events occur. relative degree deformation short-axis decreases as their ages increase. On average, severely distorted each group account for 26\% $\pm$ 9\%. possibly implies uniform $|$H$|$ $\leq$ 300 pc completeness not taken into account.