FULL-STOKES POLARIMETRY OF THE CHROMOSPHERE IN THE Hα LINE

摘要

Chromospheric magnetic fields are essentially important to understand various active phenomena in the solar atmosphere. However, polarization of the chromospheric absorption lines are weak, and therefore, it has been difficult to get magnetic maps of the chromosphere. We have developed a high-precision polarimeter with ferroelectric liquid crystals, and it enables us to get full-Stokes polarization data in the Ha line. Not only the Stokes V signals but also the Stokes Q/U signals can be detected. The results of our full-Stokes measurements suggest that the Stokes signals at the different wavelength offsets from the Ha center correspond to the magnetic fields of the different heights in the chromosphere. This means that the Ha polarimetry data have a potential to show the three-dimensional structure of the solar magnetic field.