Local twist and current helicity distributions of active region NOAA 10930

Abstract

Hinode high-quality vector magnetograms and G-band data are utilized to study the distributions of local twist αz and current helicity hc on the active region of NOAA 10930. The new findings are as follows. (1) The patches of positive and negative helicities were intermixed showing a mesh pattern in the umbra and a thread pattern in the penumbra. (2) For its main stable sunspot (MSS), there was a positive-helicity patch accounting for 43% of the umbra area surrounding the inner umbra, which had a predominantly negative helicity. For its minor rotating sunspot (MRS), there was a negative-helicity patch appearing in the umbra. (3) The fine distributions of αz and hc on a penumbral filament indicated that it may be possible for the two opposite helicities to coexist in a filament and their magnitudes were nearly equivalent. © 2009. The American Astronomical Society. All rights reserved.