The goal of my research on M31 is to understand the origin of the observed "double nucleus" found at the center of that galaxy. Normally, a galaxy will have only one "bright spot" at the isophotal center of the galaxy; but M31 shows two peaks in luminosity. (See the picture below, taken by the Hubble Space Telescope Planetary Camera)
I am attempting to solve this problem by constructing a self-consistent model based on Scott Tremaine's (Princeton University) idea of an elliptical disk of stars. Tremaine suggested that the secondary peak is due to a statistical excess of stars at apogee in an elliptical stellar disk (ring) encircling a nuclear black hole. This excess is due to the fact that stars on elliptical orbits have slower speeds at apo (the largest distance), and hence "bunch-up" at that end of the disk. The dynamical model I am working on is one envisioned by Tom Statler, my advisor. In this model, the stellar disk is essentially made-up of a series of nested "puffy" elliptical wires (orbits), which are stabilized by their own self-gravity.
salow@helios.phy.ohiou.edu Updated: 1999 October 7