Abstract
The Hanle effect in the second solar spectrum has been explored with a beam splitter based polarimeter at IRSOL in Locarno. It is the only existing imaging solar polarimeter system that is sensitive to the ultraviolet part of the spectrum, where the scattering-polarization effects are the largest. We discuss results of full vector polarimetry (all four Stokes parameters) in the Ca I 4227 and Sr II 4078 A lines in quiet and active solar regions, and show how the signatures of Hanle depolarization in Stokes Q, Hanle rotation in Stokes U, and the longitudinal Zeeman effect in Stokes V can exhibit strong spatial variations over a few arcsec. We further illustrate how the Hanle observations can be used to derive information on both the spatially unresolved and partially resolved weak magnetic fields outside the supergranulation network.
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Bianda, M., Stenflo, J.O., Solanki, S.K. (1999). Observations of the Hanle Effect in the Ca I 4227 and Sr II 4078 Å lines. In: Nagendra, K.N., Stenflo, J.O. (eds) Solar Polarization. Astrophysics and Space Science Library, vol 243. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-9329-8_3
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DOI: https://doi.org/10.1007/978-94-015-9329-8_3
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