The equation of radiative transfer in the solar interior

We re-examine the theory of collective scattering, bremsstrahlung and the transport of radiation in the solar interior, including the effects of transition-bremsstrahlung, stimulated scattering, relativistic corrections and frequency diffusion during radiative transport, which transforms the transport equation into a differential equation (in frequency) for the radiative flux. When this is taken into account the transport equation can no longer be converted into the equation of "radiative transfer" where the total flux of radiation integrated over all frequencies is related to the temperature gradient via the Rosseland mean opacity. The concept of radiative opacity can only be introduced if the frequency diffusion is ignored or treated as a perturbation. In this case the change in the radiative opacity due to these effects is discussed in view of its importance for the neutrino production rate in the solar interior and compared with previous calculations.