... galaxies generally have virial masses which are significantly larger than can be accounted for by the mass of individual ... other words, the halo of our galaxy has a velocity dispersion of 300 km/s. A cluster of galaxies has a velocity dispersion of ...
... The professional astronomer faces a similar dilemma in that most nearby galaxies, which have been used to define what we think we know about galaxy structure and evolution, are way too large to fit in a single CCD exposure. ...