Talk abstract

The only way to obtain reliable empirical information on the magnetic fields of the solar chromosphere is through the measurement and physical interpretation of the emergent polarization in truly chromospheric spectral lines. A particularly important line is H-alpha, because high-spatial resolution intensity images taken at its very line center reveal the fine-scale structuring of the quiet solar chromosphere. However, the familiar Zeeman effect as a diagnostic tool is useless in this atmospheric region. Fortunately, radiation scattering produces linear polarization signals in the very line center of H-alpha, which are modified by magnetic fields via the Hanle effect. Here we show, using a detailed radiative transfer investigation, that the peculiar scattering polarization profile observed in the H-alpha line can be exploited to obtain quantitative information on the magnetic structure of the quiet chromosphere.