| Presenter: | Rafael Manso Sainz |
| Affiliation: | Instituto de astrofisica de Canarias |
| Title: | The Hanle effect in stellar atmospheres |
| Authors: | R. Manso Sainz, J. Trujillo Bueno |
| Form: | poster |
| Abstract: | Scattering line polarization is the emission of linearly polarized light by atoms whose magnetic sublevels become unevenly populated in the absorption-emission process. The Hanle effect is the modification of such polarization signals in the presence of a magnetic field, and it is becoming increasingly useful to diagnose magnetic fields beyond the Zeeman effect limits. In optically thick media, these processes are complicated for two reasons. First, the excitation state of the atoms and the population imbalances that are the source of the polarization must be consistent with the radiation field itself (its anisotropy and polarization) that the atoms generate. Second, polarization is produced not only by differential emission, but also through selective absorption of polarization components (dichroism) by the unevenly populated lower-levels. It has been shown that some very important features of the second solar spectrum are due to this effect (e.g., the Ca~{\sc{ii}} IR triplet, the Mg~{\sc{i}} b-lines, the O~{\sc{i}}, and S~{\sc{i}} IR triplets, etc\ldots). In this talk we present the results of a systematic investigation of scattering line polarization and the Hanle effect in optically thick stellar atmospheres. We discuss how the ensuing polarization signals can be used to diagnose magnetic fields in the solar atmosphere. |
| Session: | 4. Polarized radiative transfer, theory and modeling |
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