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Paper: Some Advances in 3D-Magnetic Field Topology: an Observed Case of a "Bald Patch" Flare
Volume: 184, Third Advances in Solar Physics Euroconference: Magnetic Fields and Oscillations
Page: 65
Authors: Démoulin, P.; Aulanier, G.; Schmieder, B.
Abstract: The aim of this work is to bring observational evidences of the possible role of the "bald patch" topology in flaring events. A bald patch (or BP) is present along the photospheric inversion line where the field lines are curved-up, so when magnetic dips are present. The set of field lines associated to the BP define a separatrix where a current sheet may form. We find such configuration in AR 7722 where, on May 18, 1994, a sub-flare was observed in X-rays by Yohkoh/SXT and in Hα at NAOJ. Using the magnetohydrostatic equations derived by Low (1992), we model the magnetic field configuration by extrapolation of the Kitt Peak photospheric field, taking into account the effects of pressure and gravity. Hα flare kernels are shown to be located at the lower parts of the computed separatrices associated to bald patches (BPs). This is an evidence that BPs can be involved in flares, and that current sheets can be dissipated in low levels of the solar atmosphere.
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