The Formation of a Magnetic Channel by the Emergence of Current-carrying Magnetic Fields

Abstract

A magnetic channel - a series of polarity reversals separating elongated flux threads with opposite polarities - may be a manifestation of a highly non-potential magnetic configuration in active regions. To understand its formation we have carried out a detailed analysis of the magnetic channel in AR 10930 using data taken by the Solar Optical Telescope/Hinode. As a result, we found upflows (-0.5 to -1.0 km/s) and downflows (+1.5 to +2.0 km/s) inside and at both tips of the thread respectively, and a pair of strong vertical currents of opposite polarity along the channel. Moreover, our analysis of the nonlinear force-free fields constructed from the photospheric magnetic field indicates that the current density in the lower corona may have gradually increased as a result of the continuous emergence of the highly sheared flux along the channel. With these results, we suggest that the magnetic channel originates from the emergence of the twisted flux tube that has formed below the surface before the emergence.

11 figures, accepted for Astrophysical journal

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• Preprocessing of vector magnetograph data for a non-linear force-free magnetic field reconstruction
• Non-linear force-free field modeling of a solar active region around the time of a major flare and coronal mass ejection
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Cited by in corpus (8)

• Flare-productive active regions
• High-resolution observations of flare precursors in the low solar atmosphere
• Structure and Evolution of Magnetic Fields Associated with Solar Eruptions (Invited Review)
• Evolution of Currents of Opposite Signs in the Flare Productive Solar Active Region NOAA 10930
• Buildup and Release of Magnetic Twist during the X3.4 Solar Flare of December 13, 2006
• Spectropolarimetry of C-class flare footpoints
• Observations of a Series of Flares and Associated Jet-like Eruptions Driven by the Emergence of Twisted Magnetic Fields
• Expulsion of counter Evershed flows from sunspot penumbrae