Spectral Appearance of a 1 M⊙ Protostar

Results are presented for calculations of the emission spectrum of a one-solar-mass protostar, using a computer program which combines a numerical solution to the problem of nongrey radiative transfer in the extended protostellar atmosphere with a certain hydrodynamic code. In the calculations, LTE conditions are assumed, scattering is neglected, the gas and dust are assumed to have the same temperature, and the dust opacity is assumed to have an inverse power-law dependence on wavelength. The spectral energy distribution of the protostar is plotted and described for the optically thick and optically thin phases of collapse. The spectral sequence clearly shows the emergence of a stellar spectrum and also the gradual disappearance of the IR peak as a result of the gradual depletion of dust in the envelope. The results yield a very broad spectral energy distribution, such as is observed in T Tauri stars.