Theoretical profiles of the solar spectrum Fraunhofer lines for a six-level model of a sodium atom

Joint solutions to equations of transfer and of statistical equilibrium for a six-level model of a sodium atom are used to calculate the theoretical profiles of D-lines and a number of other sodium lines. They are shown to agree with observed profiles. The calculations were performed under the assumption of a total frequency redistribution via the equivalent two-level atom (ETA) method and of a partial frequency redistribution via a modified ETA method.