The Nuclear Disk in the Dwarf Elliptical Galaxy NGC 4486A

Many ellipticals contain nuclear disks of dust and gas. Some ellipticalscontain nuclear disks of stars that are distinct from the rest of the galaxy.We show that the dwarf E2 galaxy NGC 4486A contains both -- it is a "Rosettastone" object that tells us how nuclear disks evolve. Its properties suggestthat, as accreted gas dissipates and settles toward the center, it forms starsand builds a stellar disk. Secular growth may explain not only the mostdistinct nuclear disks such as those in NGC 4486A but also some of the diskydistortions that are commonly seen in elliptical galaxies. That is, densitydistributions may grow secularly cuspier. This would result in chaotic mixingof stellar orbits in phase space and would tend to make an elliptical galaxyevolve toward a more nearly axisymmetric shape.