Anachronistic Grain Growth and Global Structure of the Protoplanetary
  Disk Associated with the Mature Classical T Tauri Star, PDS 66
  We present ATCA interferometric observations of the old (13 Myr), nearby
(86pc) classical T Tauri star, PDS 66. Unresolved 3 and 12 mm continuum
emission is detected towards PDS 66, and upper limits are derived for the 3 and
6 cm flux densities. The mm-wave data show a spectral slope flatter than that
expected for ISM-sized dust particles, which is evidence of grain growth. We
also present HST/NICMOS 1.1 micron PSF-subtracted coronagraphic imaging of PDS
66. The HST observations reveal a bilaterally symmetric circumstellar region of
dust scattering about 0.32% of the central starlight, declining radially in
surface brightness. The light-scattering disk of material is inclined 32
degrees from face-on, and extends to a radius of 170 AU. These data are
combined with published optical and longer wavelength observations to make
qualitative comparisons between the median Taurus and PDS 66 spectral energy
distributions (SEDs). By comparing the near-infrared emission to a simple
model, we determine that the location of the inner disk radius is consistent
with the dust sublimation radius (1400 K at 0.1 AU). We place constraints on
the total disk mass using a flat-disk model and find that it is probably too
low to form gas giant planets according to current models. Despite the fact
that PDS 66 is much older than a typical classical T Tauri star (< 5 Myr), its
physical properties are not much different.
