Subarcsecond Imaging at 267 GH[CLC]z[/CLC] of a Young Binary System: Detection of a Dust Disk of Radius Less than 70 AU around T Tauri N

Abstract

The young binary system T Tauri was observed with the Owens Valley Millimeter Array in the 267 GHz continuum and HCO+ J = 3-2 emission at 0."8 resolution, with the single-baseline interferometer of the James Clerk Maxwell Telescope-Caltech Submillimeter Observatory in the 357 GHz continuum and with the W. M. Keck Telescope at lambda = 4 mu m. The 267 GHz emission is unresolved, with a flux of 397+/-35 mJy, located close to the position of the optical star T Tau N. An upper limit of 100 mJy is obtained toward the infrared companion T Tau S. The 357 GHz continuum emission is unresolved, with a flux of 1.35+/-0.68 Jy. HCO ^{+} J = 3-2 was detected from a 2" diameter core surrounding T Tau N and S. Both stars are detected at 4 mu m, but there is no evidence of the radio source T Tau R. We propose a model in which T Tau S is intrinsically similar to T Tau N but is obscured by the outer parts of T Tau N's disk. A fit to the spectral energy distribution (SED) between 21 cm and 1.22 mu m is constructed on this basis. Adopting an r ^{-1} surface density distribution and an exponentially truncated edge, disk masses of 0.04+/-0.01 and 6x10^{-5} to 3x10^{-3} Msolar are inferred for T Tau N and T Tau S, respectively. A 0.005-0.03 Msolar circumbinary envelope is also required to fit the millimeter to mid-infrared SED.