Member selection process for the α Per cluster. The left and center columns display Galactic XYZ coordinates centered on the Sun, and the right-hand side column shows deprojected tangential velocities. The top row shows kernel density maps centered on α Per that distinctly highlight the cluster populations. The line of sight (dashed line) and the Galactic orbit of α Per (solid line) are also shown. The bottom panels present the member selection procedure, in which first a radial filter is applied in deprojected tangential velocities (red sources), followed by DBSCAN clustering in the XYZ parameter space to produce the final selection (blue dots).