This paper highlights very recent advances concerning the identification of new mechanisms that introduce polarization in spectral lines, which turn out to be key for understanding some of the most enigmatic scattering polarization signals of the solar visible spectrum. We also show a radiative transfer prediction on the scattering polarization pattern across the Mg iih & k lines, whose radiation can only be observed from space.

We observed the magnetic field of the CP star $\alpha^2$ CVn with the 6-m telescope and the echelle-spectrometer (spectral resolution $R=50000$, spectral range $\lambda\lambda 3400--4100$) using a CCD device and Zeeman analyzer. The longitudinal magnetic field $B_{\rm e}$ measured using lines with wavelengths shorter than the Balmer jump ($\lambda 3646$) are systematically 25% smaller at all rotational phases compared with measurements made in the region $\lambda > 3646$. Because in general lines with $\lambda > 3646$ form at deeper levels than lines with $\lambda < 3646$ we get additional evidence for the increase of $B_{\rm e}$ with depth in the atmosphere of $\alpha^2$ CVn.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html