Imaging the HL Tauri Disk at λ = 2.7 Millimeters with the BIMA Array

Abstract

We have obtained a subarcsecond image of the disk associated with the T Tauri star HL Tau at a wavelength of 2.7 mm using the new high-resolution capability of the BIMA Array. The disk is elongated with a deconvolved Gaussian source size of 1."0 +/- 0."2 x 0."5 +/- 0."2, implying a semimajor axis of 70 +/- 15 AU for a distance of 140 pc; the minor axis may be unresolved. The position angle of the major axis (125 deg +/- 10 deg) is orthogonal to the axis of the optical jet. The disk centroid is coincident with the VLA lambda = 3.6 cm source position and nearly coincident with recent measurements of the near-infrared emission peak. The lambda = 2.7 mm images, along with previous interferometric measurements at lambda = 0.87 mm and flux measurements from 10 mu m to 1.3 cm, are well fitted by a simple power-law disk model with a shallow radial dependence to the surface density [ Sigma (r) ~ r0 to r-1], an outer radius between 90 and 160 AU, and a dust opacity law proportional to nu 1.