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 α _z and current helicity h_c 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 α _z and h_c 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.