ACS Coronagraphic Observations of Transitional Debris Disks: HD100546 and HD163296
          David R. Ardila, JHU
          David A. Golimowski, JHU
          John E. Krist, JPL
          Mark Clampin, NASA/GSFC
          Holland C. Ford, JHU
          Garth D. Illingworth, UCSC/Lick
          ACS GTO Team

          We present ACS/HRC multicolor coronagraphic images of the dusty disks around the Herbig AeBe stars HD100546 and HD163296.  The latter is the oldest Herbig Ae/Be star associated with HH objects. The disks are optically thick and show significant amounts of structure.  Our images provide important observational constraints regarding the origins of these structures. The B, V, and I bands allow us to study opacity changes in the resolved disk as well as precisely measuring, for the first time, their optical colors.