Rotation curve of M 33 (filled triangles) and the best-fitting model (solid line) for a dark matter halo with a constant density core (bottom panel) and according to MOND (top panel). The small and large dashed lines (red and blue in the online version) show the gas and stellar disk Newtonian contributions to the rotation curves, respectively; the dark halo contribution in the bottom panel is shown with a long dashed line.