M31 is the nearest large spiral to us. Previously thought to be "like the Milky Way, only more so", recent work has shown that its structure (and likely history) are quite different. My collaborators and I have shown that M31 has a thin disk of globular clusters, many of which are ancient, and, using planetary nebula kinematics, discovered a new satellite, And VIII, which is likely to be associated with the giant star stream which extends south of M31. We have also shown that its large R**1/4 bulge dominates kinematically as well as photometrically out to at least 20 kpc from the center.
The stunning picture below is by astrophotographer Robert Gendler:
Publications:
(This work is supported by NSF grant AST-9624542)