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Session 113 - Observations of the Circumstellar Environment of YSOs.
Oral session, Thursday, January 18
Corte Real, Hilton
We have obtained a sub-arc-second image of the disk associated with the TTauri star HL Tau at a wavelength of 2.7mm using the new high resolution capability of the BIMA array. The disk is elongated with a deconvolved Gaussian source size of 1.0\pm0.2\arcsec\ \times 0.5\pm0.2\arcsec, implying semimajor and semiminor axes of 70\pm15 AU and 35\pm15 AU, respectively, for a distance of 140 pc. The position angle of the major axis (125\deg\pm10\deg) is orthogonal to the axis of the optical jet, and the aspect ratio of the axes suggests an inclination angle between 25\deg\ and 75\deg\ for a thin disk. The disk centroid is coincident with the VLA \lambda=3.6cm source position and nearly coincident with recent measurements of the near-infrared emission peak. The \lambda=2.7mm images, along with previous interferometric measurements at \lambda=0.87mm and flux measurements from 10 microns to 1.3cm, are well fitted by a simple power-law disk model with a shallow radial dependence to the surface density (\Sigma (r) \propto r^0 to r^-1), an outer radius between 90 and 160 AU, and a dust opacity law proportional to \nu^1.
