The effects of non-coherent electron scattering on spectral line formation

Abstract

Spectral line profiles from a plane-parallel homogeneous atmosphere have been calculated for the complete and partial redistribution mechanisms (CRD and PRD) including coherent and noncoherent electron scattering. It is found that in all the cases where the electron scattering coefficient is more than the continuous absorption coefficient, there are measurable changes in the spectral line profiles. In such situations, the PRD profiles have more emission hump compared to CRD profiles in the intermediate frequency range. Extended wings and additional broadening of the line profiles are obtained for the case of noncoherent electron scattering compared to coherent electron scattering. These results have implications in the derivation of physical properties (for example, microturbulent velocities) of stellar atmospheres from spectral lines.