Chromospheric polarization in the photospheric solar oxygen infrared triplet.

Figure caption: The Stokes I and Q/I profiles of the IR triplet of O I calculated in the FAL-C semi-empirical model for a line of sight with μ = 0.1. The positive reference direction for Stokes Q is the parallel to the nearest limb. Top panels: the Stokes
Figure caption: The Stokes I and Q/I profiles of the IR triplet of O I calculated in the FAL-C semi-empirical model for a line of sight with μ = 0.1. The positive reference direction for Stokes Q is the parallel to the nearest limb. Top panels: the Stokes
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References
2015, ApJ, 808, L13

We present multilevel radiative transfer modeling of the scattering polarization observed in the solar O I infrared triplet around 777 nm. We demonstrate that the scattering polarization pattern observed on the solar disk forms in the chromosphere, far above the photospheric region where the bulk of the emergent intensity profiles originate. We investigate the sensitivity of the polarization pattern to the thermal structure of the solar atmosphere and to the presence of weak magnetic fields (0.01 –100 G) through the Hanle effect, showing that the scattering polarization signals of the oxygen infrared triplet encode information on the magnetism of the solar chromosphere.

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