Figure 4: A log-log plot of the velocity dispersion in hot stellar systems against the characteristic size for different classes of objects. The star points are globular clusters, the solid round points are massive molecular clouds in the Galaxy, the crosses are luminous elliptical galaxies, the triangles are dwarf spheroidal galaxies, the dashes are compact dwarf ellipticals, and the squares are X-ray emitting clusters of galaxies. The solid line corresponds to and the dashed lines show a factor of 2.2 variation on each side. The references to the relevant observational papers may be found in [15].