The Second Solar Spectrum


The Sun’s radiation becomes linearly polarized by coherent scattering processes in the solar atmosphere. With a novel imaging polarimeter (Zurich Imaging Stokes Polarimeter I) that achieves a precision of 10(-5) in the degree of polarization, the previously largely unexplored territory of scattering physics on the Sun is now fully accessible. The observations reveal a polarized spectrum that looks very different from the ordinary, unpolarized solar spectrum but has an astounding wealth of spectral structures from atoms as well as molecules. This second solar spectrum will be used as a new source of information to learn more about atomic physics, abundances and isotope ratios, radiative transfer physics, solar magnetic fields, and the thermodynamics of the solar atmosphere.

American Astronomical Society Meeting Abstracts #188