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 870 micron and 3.4 mm from the
Submillimeter Array (SMA) and Combined Array for Research in Millimeter
Astronomy (CARMA). 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 0.007 M_sun, assuming optically thin,
isothermal dust emission. The millimeter spectral index is observed to be quite
shallow at all the spatial scales probed; alpha ~ 2, implying a dust opacity
spectral index beta ~ 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\arcmin\
image, spectral energy distribution, and mid-infrared spectrum. The best
fitting model has a disk radius of R = 125 AU, is highly flared (H ~ R^1.3),
has a radial density profile rho ~ R^-2.5, and has a mass of 0.0075 M_sun. 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 is 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 ~1 micron-sized dust grains.
