Resonance line polarization in the presence of wave motion

Abstract

The effect of wave velocity on resonance line polarization is studied. We assumed a photosphere - chromosphere type of temperature structure for the atmosphere with plane parallel symmetry. The "Discrete Space Theory technique" to solve the polarized radiative transfer in the presence of velocity fields and under the assumption of Complete Redistribution mechanism is briefly described along with the numerical checks performed. We considered both sinusoidal and sawtooth wave functions for the velocity in the medium. We find the linear polarization in the resonance lines to be increased when averaged over the whole period of the wave compared to the static medium case. The sawtooth wave shows a different average polarization profile compared to the sinusoidal wave. Line center intensity as well as the polarization vary with a period which is half of that of the wave. The variation amplitude for polarization is higher compared to the intensity towards the limb. Hence polarization in the limb may serve as an additional useful information to characterize the wave.