Study of Magnetic Channel Structure in Active Region 10930

Abstract

The concept of was flrst introduced by Zirin and Wang (1993). They were deflned as a series of oppositely directed vertical-fleld inversions separated by extremely narrow elongated transverse flelds. In this paper, we utilized unprecedented flltergraph and spectropolarimetry observations from Hinode, and studied the evolution and physical properties of channel structure of AR 10930 in detail. We found that: (1) Channels are associated with new ∞ux emergence in the middle of existing penumbra connecting the ‐ sunspot. (2) The width of each channel is in the order of 1 arsec or less. (3) The line-of-sight magnetic gradient is highest in the channel, 2.4 to 4.9 G/Km. (4) The flelds are highly sheared and inclined with a median shear angle around 64 degrees and inclination angle around 25 degrees. (5) Using Non-Linear Force-Free Field (NLFF) extrapolation, we derive a near surface current system carrying strong electric current in the order of 1 £ 10 14 Amps. (6) The X3.4 ∞are on 2006 December 13 occurred during the period that the channels rapidly formed, but a few hours before the maximum phase of channel structure development. Based on the observational evidence, we propose that the channels are formed during the emergence of a sequence of magnetic bipoles that are squeezed in the compact penumbra of the ‐ sunspot and they are highly non-potential. Formation of channels might be a precursor of major ∞ares.