| Presenter: | Javier Trujillo Bueno |
| Affiliation: | Instituto de Astrofísica de Canarias |
| Title: | The scattering polarization of the Sr~{\sc{i}} 4607~{\AA} line at the diffraction limit resolution of a 1-m telescope |
| Authors: | J. Trujillo Bueno, N. Shchukina |
| Form: | poster |
| Abstract: | One of the greatest challenges in solar spectropolarimetry in coming years will be to observe the Second Solar Spectrum at sub-arcsecond spatial resolution. Such type of scattering polarization observations, ideally in photospheric and chromospheric lines simultaneously, would probably allow us to discover hitherto unknown aspects of the Sun's hidden magnetism. In the ``quiet" regions of the solar atmosphere, which cover most of the solar surface at any given time during the solar magnetic activity cycle, there are two main reasons for expecting spatial variability in the linear polarization signals produced by scattering processes (e.g., Trujillo Bueno et al.\ 2004). First, the atmospheric inhomogeneities produced by the solar surface convection lead to horizontal fluctuations in the anisotropy of the radiation field, as well as to symmetry breaking effects, which must have their impact on the polarization of the emergent radiation. Second, the scattering polarization signals are sensitive to magnetic fields via the Hanle effect, and will therefore show horizontal variability if the statistical properties of the hidden field are not homogeneous. Therefore, to detect such horizontal fluctuations in $Q/I$ and $U/I$ across a two-dimensional field of view would be of fundamental importance to understand the quiet Sun magnetism. Fortunately, there are a few spectral lines, characterized by a particularly high scattering polarization amplitude, for which such a goal can be achieved with the help of a 1-m solar telescope equipped with a suitable polarimeter. Here we show examples of such high-spatial-resolution scattering polarization signals for the familiar case of the Sr~{\sc{i}} 4607~{\AA} line. Interestingly, the $Q/I$ and $U/I$ line-center images we have obtained at increasing distances from the solar limb show sizable fluctuations with a fascinating small-scale pattern of great diagnostic value. References: Trujillo Bueno, J., Shchukina, N., \& Asensio Ramos. A. 2004, Nature, 430, 326 |
| Session: | 1. Second Solar Spectrum |
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