  A series of self-consistent, three-dimensional continuum radiative transfer
models are constructed of the pre-protostellar core L1544, with the results
compared with existing SCUBA and ISO data. The source is well-fit by a prolate
spheroid, having an ellipsoidal power-law density distribution of index m ~ 2
(1.75 < m < 2.25) in to at least r ~ 1600AU. For r<1600 AU, the data are
consistent with either an extension of the power law to smaller radii, or a
flattened (Bonner-Ebert like) density distribtion. We can further constrain the
optical depth along the short axis at 1300um to be ~ 5e-3, the central
luminosity to be L < 1e-3 solar luminosities, the long axis diameter D ~ 0.1
pc, the axis ratio to be q ~ 2, and the external ISRF to be similar to that
defined by Mathis, Mezger, & Panagia (1983) to within 50 per cent. The outer
diameter and axis ratio may each be somewhat larger due to potential on-source
chopping in the observations, and the projection of the long axis onto the
plane of the sky. While these results are similar to those inferred directly
from observations or spherical modeling due to the source transparency at
submillimeter wavelengths, we infer a smaller size, lower mass, and higher
optical depth / column density, exposed to a stronger external radiation field
than previously assumed. Finally, we find that both the spectral energy
distribution (SED) and surface brightness distribution are necessary to
constrain the source properties in this way.
