Solar Transients and Space Weather (STSW)
Science Highlights
Observations of solar scattering polarization at high spatial resolution
The weak, turbulent magnetic fields that are hypothesized to permeate most of the solar photosphere are difficult to observe, because the well-known Zeeman effect is virtually blind to them. The Hanle effect, acting on the scattering polarization in suitable lines, in principle can be used as a diagnostic for these fields. However, the prediction that the majority of the weak, turbulent field resides in intergranular lanes also poses significant challenges to scattering polarization observations because high spatial resolution is usually difficult to attain. Hinode-SOT offers unprecedented spatial resolution in combination with high polarimetric sensitivity. The CN band is known to have a significant scattering polarization signal, and is sensitive to the Hanle effect. We use Hinode/SOT observations in the CN band to show that the scattering polarization for granules (i.e., regions brighter than the median intensity of non-magnetic pixels) is significantly larger than for intergranules. Snik, de Wijn, et al derive that the intergranules (i.e., the remaining non-magnetic pixels) exhibit (9.8 ± 3.0)% less scattering polarization for 0.2 < µ ≤ 0.3, although systematic effects cannot completely be excluded.