What are hot and cold stellar systems? My idea of the matter is: hot stellar systems are which form of objects which have a velocity standard deviation comparable to their mean velocity. Is this correct? If it is, is there a $\frac{\sigma_v}{&lt;v&gt;}$ boundary, which draws a line between hot and cold stellar systems?
I was wrong, hot systems are where members have velocities which have magnitudes in all directions in the same order (causing them to have roundish shape), while cold dynamical systems are where random motions do not have the same average magnitude in all directions (ie disc galaxies).