Solution of the radiative-transfer equations with an azimuth-averaged Hanle phase matrix

Abstract

The system of radiative-transfer equations for polarized radiation is solved analytically using an azimuth-averaged Hanle phase matrix. A Milne-Eddington model with a constant ratio of the line and continuum absorption coefficients and a linear dependence of the source function on optical depth is adopted for the atmosphere. The vector magnetic field is taken to be constant with optical depth. The dependence of the linear polarization obtained during observations at the solar limb on the magnitude and inclination of the magnetic field to the normal of the atmosphere is presented as an illustration of the theoretical computations. The measured polarization corresponds to two magnetic-field values and several possible field inclinations. The measured polarization is directly proportional to the quantum coefficient W2 determining the resonance polarization in lines.