AB Aurigae Resolved: Evidence for Spiral Structure
          Stuartt Corder
          Josh Eisner
          Anneila Sargent

          We present high angular resolution (~2'') 13CO(J=1-0) line and 2.7 mm continuum emission images of the Herbig Ae star AB Aurigae.  We resolve a circumstellar disk of diameter 780 AU (FWHM) with a velocity pattern consistent with a purely rotational disk at inclination 21.5 degrees.  Using Keplerian disk models, we find a central source dynamical mass of 2.8 Msun.  We also confirm the existence of spiral structure in the disk as suggested by near-IR scattered light images and show that the spiral arms represent density contrasts in the disk. We discuss the application of these models to the Herbig Ae stars CQ Tau and MWC 758.