Rayleigh Scattering in the Atmospheres of Hot Stars

Rayleigh scattering is the process of interaction of photons with bound electrons. This process is often neglected in hot star model atmospheres. The reason is that a large fraction of hydrogen and helium atoms are singly ionized, and the scattering cross section of singly ionized helium is by two orders of magnitude lower than the neutral hydrogen scattering cross section. We studied the effect of Rayleigh scattering by neutral hydrogen and singly ionized helium in the stellar model atmospheres. We computed the models for the B-type stars with solar composition and helium over-abundant atmospheres N(He)/N(H) = 10. The results show that Rayleigh scattering by singly ionized helium can be a significant opacity source for the helium-rich stars, and this process can be included in hot star model atmospheres.