A new approach to multi-level non-LTE radiative transfer problems (Q1074334)

This is an interesting paper which describes a new approach for solving multi-level non-local thermodynamic equilibrium radiative transfer problems. The transport of radiation in spectral lines plays an important role in determining the energy and momentum balance in the outer layers of stellar atmospheres. The approach of the authors involves: (a) linearization of the statistical equilibrium equations and the radiative transfer equation, (b) use of appropriate preconditioning, and (c) simplification of the numerical representation of the radiative transfer process. The authors develop numerical methods from certain simplifications which are natural from analyzing the physics of the problems considered.