Two-dimensional maps of mean radial velocity for high-mass stars (M ≥ 2 M_⊙, left panel) and low-mass stars (right panel). Stars belonging to the same Voronoi bin are color-coded according to the mean radial velocity, while black lines are iso-density contours of the respective populations enclosing about 12% (solid line), 39% (dashed line), and 67% (dash-dotted line) of the underlying density distribution.