An Investigation of ResonanceLine Scattering by the Monte Carlo Technique
Abstract
The problem of photon diffusion through a purely scattering atmosphere is investigated by means of the Monte Carlo technique for two types of scattering: (1) complete redistribution and (2) coherent scattering in the rest frame of the atom which leads to partially coherent scattering in the external frame. The Monte Carlo techniques are applied to Lymana photons generated at a point source at the center of a planeparallel slab of large optical thickness. The mean number of scatterings required for escape, (N), is computed for both types of scattering. For thick slabs (N) is found to be much greater under partially coherent conditions. As a result the source function should approach the equilibrium value at smaller optical depths than one predicts under complete redistribution. In addition it is found that, under partially coherent scattering, photons tend to diffuse more easily in space, but less easily in frequency than under complete redistribution. Thus for complete redistribution the photons are more likely to remain in the vicinity of their origin until they escape from the atmosphere as the result of a single, large frequency shift
 Publication:

The Astrophysical Journal
 Pub Date:
 May 1968
 DOI:
 10.1086/149566
 Bibcode:
 1968ApJ...152..493A