Dynamics of Elliptical Galaxies and Other Spheroidal Components

Elliptical galaxies are the simplest type of galaxy and therefore the natural starting point for studies of galaxies in general. Furthermore, it has often been argued (e.g. de Vaucouleurs 1959, Ostriker 1977) that at the heart of every disk galaxy there sits a small elliptical, the bulge, around which the disk that now dominates the light distribution has been assembled. So it is possible that ellipticals and bulges are, so to speak, the founding fathers of the realm of the nebulae, and as such may have profoundly influenced the form of the com­ ponents into which the majority of the luminous matter in the Universe sub­ sequently settled. For many years neither elliptical galaxies nor bulges received the attention warranted by their intrinsic interest. There were two reasons for this. The subsidiary reason was that it was widely felt that elliptical galaxies are so simple that their structures could be inferred by Plato' s preferred method of research-pure thought. Surely these systems were isothermal bodies that rotate more or less rapidly according to their degree of equatorial-flattening. Galaxies of this type did not seem mysterious. However, the principal reason why ellipticals tended to be neglected in favor of disk galaxies was the great labor involved in obtaining reliable photometry or measuring their mean and