Position of molecular clouds in NGC 628. From top left to bottom right: colors correspond to the CO luminous masses, CO velocity linewidth, alpha virial parameter, and gas surface density, truncated to 8.6 × 10⁶ M_⊙, 15 km s⁻¹, 3.0, and 200 M_⊙ pc⁻², respectively. The size of each symbol represents the physical size of the molecular cloud. Indicated in each panel is the headlight molecular cloud (L1) and the nine most massive molecular clouds (L2−L10). The light yellow areas show the position of corotation regions at 3.2 kpc (red circles) and 5.1 kpc (green circles). The contours correspond to the 5σ level of the CO(2–1) moment zero map. Offset positions are from the galactic center.