Subarcsecond VLA Observations of HL Tauri: Imaging the Circumstellar Disk

We report high-resolution observations of HL Tau at 6 cm, 3.6 cm, and 7 mm using the VLA in B configuration. The new centimeter wavelength data are in accord with previous observations—taking into account resolution and sensitivity—and provide no evidence for time variability. At 7 mm, we have used a "fast-switching" calibration technique to partially overcome the problem of atmospheric phase fluctuations and achieve subarcsecond angular resolution. The 7 mm image, which is dominated by dust emission, shows a flattened structure with Gaussian deconvolved size (0 75 ± 0 1) × (0 35 ± 0 1) [(105 ± 14) × (50 ± 14) AU] and major axis P.A. 125° ± 10°. This orientation is similar to that found at shorter wavelengths and is approximately orthogonal to the optical jet axis, consistent with a dusty accretion disk surrounding the star.