We present a study of the pre-protostellar core L1544 .
A series of self-consistent , three-dimensional continuum radiative transfer models are constructed .
The outputs of these models are convolved with appropriate telescope beam responses , and compared with existing SCUBA data .
The resulting comparison allows us to constrain the structure of L1544 .
We find that the source is well-fit by a prolate spheroid , having an ellipsoidal power-law density distribution of index m \sim 2 ( 1.75 < m < 2.25 ) in to at least r \sim 1600 AU .
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 .
Furthermore , we find an optical depth along the short axis at 1300 \mu m of \tau _ { 1300 , \mathrm { short } } = 5 \times 10 ^ { -3 } ( 2 \times 10 ^ { -3 } < \tau _ { 1300 , \mathrm { short } } < 8 \times 10 ^ { -3 } ) , a central luminosity L _ { * } = 0 ( < 10 ^ { -3 } L _ { \odot } ) , a long axis diameter D = 0.1 pc ( 0.08 < D ( \mathrm { pc } ) < 0.16 ; 16000 < D ( \mathrm { AU } ) < 32000 ) , an axis ratio q = 2 ( 1.7 < q < 2.5 ) , and an external ISRF 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 , and even a modest variation in \chi ^ { 2 } can significantly alter the fit quality .