Vector Magnetic Fields, Sub-surface Stresses and Evolution of Magnetic Helicity

Journal of astrophysics and astronomy

Alexei Pevtsov¹  Richard Canfield1¹ 

[1]Department of Physics, Montana State University, Bozeman, Montana 59717-3840.$$

关键词: Magnetic fields;    currents;    magnetic helicity.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Observations of the strength and spatial distribution of vector magnetic fields in active regions have revealed several fundamental properties of the twist of their magnetic fields. First, the handedness of this twist obeys a hemispheric rule: left-handed in the northern hemisphere, right-handed in the southern. Second, the rule is weak; active regions often disobey it. It is statistically valid only in a large ensemble. Third, the rule itself, and the amplitude of the scatter about the rule, are quantitatively consistent with twisting of fields by turbulence as flux tubes buoy up through the convection zone. Fourth, there is considerable spatial variation of twist within active regions. However, relaxation to a linear force-free state, which has been documented amply in laboratory plasmas, is not observed.

【 授权许可】

Unknown