MODELS OF THE SPECTRAL ENERGY-DISTRIBUTIONS OF FU ORIONIS STARS

Observed spectral energy distributions (SEDs) of FU Orionis, V1057 Cyg ni, and V1515 Cygni are fitted by theoretical spectra, which are calcu lated from models consisting of outbursting accretion disks together w ith flattened envelopes. Temperature in the envelopes is determined by approximate radiative equilibrium with a central source. The disk mod els are two-dimensional and include reprocessing of disk radiation by the disk. The theoretical spectra are calculated using a radiative tra nsfer code and frequency-dependent opacities, at a spectral resolution of lambda/Delta lambda = 14. Excellent matches to the data are obtain ed for all three objects with reasonable model parameters. Radiative t ransfer is also used to calculate a time series of images showing the progress of an outburst as imaged through a B-band filter.