Full non-LTE spectral line formation II. Two-distribution radiation transfer with coherent scattering in the atom’s frame

Abstract

In this article we discuss a method for obtaining a numerical solution to the so-called full nonlocal thermodynamic equilibrium (nonLTE) radiation transfer problem. More specifically, the usual numerical iterative methods for non-LTE radiation transfer are coupled with that formalism and new numerical additions are explained in detail. We benchmarked the whole process with the standard non-LTE transfer problem for a two-level atom with Hummer’s RI−A partial frequency redistribution function. Finally, we present new quantities, such as the spatial distribution of the velocity distribution function of excited atoms, which can only be accessed by adopting a more general frame for non-LTE radiation transfer, such as the one we propose here.