A RADIATIVE-TRANSFER CALCULATION USING R(III) IN AN EXPANDING SPHERICALLY SYMMETRICAL STELLAR ATMOSPHERE

With the availability of very high-resolution stellar spectra, even small differences between line profiles resulting from complete redistribution and partial frequency redistribution may be important in the quantitative analysis of stellar spectra. A differentially expanding and spherically symmetric stellar envelope is considered in order to study the effects of the angle-averaged partial frequency redistribution function R(III) on spectral line formation. The line transfer equation is solved in the rest frame of the star, assuming a two-level atomic model. The differences between the emergent mean intensity profiles resulting from complete redistribution and the angle-averaged R(III) are found to be much smaller in expanding spherically symmetric stellar atmospheres than has been reported previously for plane-parallel atmospheres.