COMPUTER-SIMULATIONS OF INTERACTING GALAXIES IN COMPACT-GROUPS AND THE OBSERVED PROPERTIES OF CLOSE BINARY GALAXIES

Theoretical models have been constructed for the samples of close bina ry galaxies by Karachentsev. It is assumed that initially the galaxies were members of small groups which degenerated to binary systems via mergers. The samples obtained in this way are compared with the observ ed sample. We find that it is possible to get a good match between the observed and the theoretical distributions of the projected separatio ns and radial velocities of the binaries. This allows us to overlay th e theoretical mass distribution with the observed luminosity distribut ion of the galaxies in question and to determine the average mass-to-l ight ratio for the systems. As this method is insensitive to small num bers of optical pairs or otherwise unbound galaxies, the resulting mas s-to-light ratio of 50 solar units should be a robust estimate. Furthe r support for the merger scenario is provided by the larger than avera ge luminosity in close binary pairs, as well as their relatively short time scales for a merger to a single galaxy. The pairs also typically contain signs of interaction which further confirm the model assumpti on that the close binary pairs are transitionary systems. (C) 1996 Ame rican Astronomical Society.