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Published June 1, 2009 | Published
Journal Article Open

Grain Growth and Global Structure of the Protoplanetary Disk Associated with the Mature Classical T Tauri Star, PDS 66


We present Australia Telescope Compact Array interferometric observations of the old (13 Myr), nearby (86 pc) classical T Tauri star (cTTS), PDS 66. Unresolved 3 and 12 mm continuum emission is detected toward PDS 66, and upper limits are derived for the 3 and 6 cm flux densities. The millimeter-wave data show a spectral slope flatter than that expected for interstellar medium-sized dust particles, which is evidence of grain growth. We also present HST/NICMOS 1.1 μm point-spread-function-subtracted coronagraphic imaging observations of the circumstellar environment of PDS 66. The Hubble Space Telescope observations reveal a bilaterally symmetric circumstellar region of dust scattering ~0.32% of the central starlight, declining in surface brightness as r ^(–4.53). The light-scattering disk of material is inclined 32° ± 5° from a face-on viewing geometry, 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. 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 cTTS (≤5 Myr), its physical properties are not much different.

Additional Information

© 2009. The American Astronomical Society. Print publication: Issue 2 (2009 June 1). Received 2008 October 3, accepted for publication 2009 March 23. Published 2009 May 11. We are grateful to the anonymous referee for providing useful suggestions that greatly improved this paper.We thank the FEPS team for their valuable contributions and encouragement. S.R.C. thanks E. Mamajek for his useful suggestions and making us aware of his unpublished work, which both improved the quality of this paper. We also thank C.P. Dullemond for providing CGPLUS. S.R.C. wishes to thank Stéphane Herbert-Fort for many useful discussions. The Australia Telescope Compact Array is part of the Australia Telescope which is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. This work is based, in part, on observations with the NASA/ESA Hubble Space Telescope (HST), which is operated by AURA, under NASA contract NAS5-26555. The HST observations are associated with GO programs 10527 and 10177 with support provided by NASA grants through STScI. M.R.M., I.P., and S.R.C. gratefully acknowledge support from NASA Astrobiology Institute through LAPLACE. FEPS was supported through NASA contracts 1224768, 1224634, and 1224566, managed by JPL. Facilities: ATCA, HST (NICMOS)

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