Multi-level non-LTE radiative transfer in expanding shells

Abstract We present a new and general method for the solution of complex multi-level non-LTE radiative transfer problems both in static and moving media. The method is based on the approximate Λ-iteration method and is a direct extension of the scheme devised by Rybicki and Hummer (1991). We demonstrate that this method is able to treat both active continua and overlapping lines with relatively small amount of computer resources. Some simplified test cases are presented and discussed.