A Model for a Two Component Galaxy.

Extract

As most of today approaches to the problem of galactic structure are based on the consideration of the two main components of a galaxy, halo and disk, it was thought that even simple models of such kinds of double structures, based only on the application of general theorems, could be of some use, at least for simplified outlooks concerning galac tic evolution. With this aim in mind, we have undertaken the treatment of bodies constituted by two different axially deformed polytropic structures, homocentrical and coaxial, with arbitrary values for the two masses M_I and M_II, the two radii a_I and a_II of the undeformed objects (a_I a_II) and polytropic indices n_I and n_II, interacting with each other only gravitationally. The flattening of the spheroids is assumed to be due to solid body rotation and tidal interaction, and the treatment follows closely the method used for such single structures by Chandrasekhar and Lebovitz.