Abstract:
The Ba ii D2 line at 4554 Å is a good example, where the F-state interference effects due to the odd isotopes produce polarization profiles, which are very
different from those of the even isotopes that do not exhibit F-state interference. It is
therefore necessary to account for the contributions from the different isotopes to understand the observed linear polarization profiles of this line. In this paper we present
radiative transfer modeling with partial frequency redistribution (PRD), which is shown
to be essential to model this line. This is because complete frequency redistribution
(CRD) cannot reproduce the observed wing polarization. We present the observed and
computed Q/I profiles at different limb distances. The theoretical profiles strongly depend on limb distance (µ) and the model atmosphere which fits the limb observations
fails at other µ positions.
