The polarization properties of model sunspots: the broad-band polarization signature of the Schlüter-Temesvary representation

The properties and diagnostic content of integrated-over-wavelength Zeeman-induced polarization in spectral lines formed in sunspots are investigated. The net circular polarization (NCP) generated by a continuously varying velocity field parallel to a constant magnetic field with arbitrary inclination is shown to follow the algebraic expression for the step-velocity model of Auer and Heasley (1978). Although application of the analysis to parameters representative of sunspots fails to yield the observed broadband NCP radius pattern, the introduction of magnetic field gradients and magnetooptical birefringence is found to result in a pattern similar to that observed. 24 references.