MODELING THE RESOLVED DISK AROUND THE CLASS 0 PROTOSTAR L1527

We present high-resolution sub/millimeter interferometric imaging of the Class 0 protostar L1527 IRS (IRAS 04368+2557) at lambda = 870 mu m and 3.4 mm from the Submillimeter Array and Combined Array for Research in Millimeter Astronomy. We detect the signature of an edge-on disk surrounding the protostar with an observed diameter of 180 AU in the sub/millimeter images. The mass of the disk is estimated to be 0.007M(circle dot), assuming optically thin, isothermal dust emission. The millimeter spectral index is observed to be quite shallow at all the spatial scales probed: alpha similar to 2, implying a dust opacity spectral index beta similar to 0. We model the emission from the disk and surrounding envelope using Monte Carlo radiative transfer codes, simultaneously fitting the sub/millimeter visibility amplitudes, sub/millimeter images, resolved L' image, spectral energy distribution, and mid-infrared spectrum. The best-fitting model has a disk radius of R = 125 AU, is highly flared (H alpha R-1.3), has a radial density profile rho alpha R-2.5, and has a mass of 0.0075M(circle dot). The scale height at 100 AU is 48 AU, about a factor of two greater than vertical hydrostatic equilibrium. The resolved millimeter observations indicate that disks may grow rapidly throughout the Class 0 phase. The mass and radius of the young disk around L1527 are comparable to disks around pre-main-sequence stars; however, the disk is considerably more vertically extended, possibly due to a combination of lower protostellar mass, infall onto the disk upper layers, and little settling of similar to 1 mu m-sized dust grains.