Abstract
The structure of the photospheric magnetic field during solar flares is examined using echelle spectropolarimetric observations. The study is based on several Fe i and Cr i lines observed at locations corresponding to brightest Hα emission during thermal phase of flares. The analysis is performed by comparing magnetic-field values deduced from lines with different magnetic sensitivities, as well as by examining the fine structure of I±V Stokes-profiles’ splitting. It is shown that the field has at least two components, with stronger unresolved flux tubes embedded in weaker ambient field. Based on a two-component magnetic-field model, we compare observed and synthetic line profiles and show that the field strength in small-scale flux tubes is about 2 – 3 kG. Furthermore, we find that the small-scale flux tubes are associated with flare emission, which may have implications for flare phenomenology.
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The authors thank Philippa Browning for useful comments from which the article strongly benefited. MG is supported by the Science and Technology Facilities Council (UK).
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Gordovskyy, M., Lozitsky, V.G. Observations of Unresolved Photospheric Magnetic Fields in Solar Flares Using Fe i and Cr i Lines. Sol Phys 289, 3681–3701 (2014). https://doi.org/10.1007/s11207-014-0546-2
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DOI: https://doi.org/10.1007/s11207-014-0546-2