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| Paper: |
What is the Most Important Origin of the Coronal Helicity? |
| Volume: |
383, Subsurface and Atmospheric Influences on Solar Activity |
| Page: |
213 |
| Authors: |
Tian, L. |
| Abstract: |
23 active regions (ARs) with well-defined SXR sigmoids are selected to study which is the more important origin of the coronal helicity — the emergence of magnetic fields or photospheric horizontal motions. The radial magnetic flux of each polarity, the helicity injection rate, and total helicity flux (ΔHlct) are calculated using local correlation tracking technique and MDI 96m line-of-sight magnetograms, and the helicity budget of the differential rotation (ΔHrot) is also estimated. It is found that six ARs inject helicity flux greater than 1.0 × 1043Mx2 (ΔH = ΔHlct − ΔHrot), in a sample of seven ARs with emerging magnetic flux greater than 1.0 × 1022Mx. On the other hand, in sixteen ARs with emerging magnetic flux less than 1.0 × 1022Mx, only four ARs inject helicity flux greater than 1.0×1043Mx2, which denotes the main contribution of the horizontal motions. The statistical results suggest that the horizontal motions are not important to the coronal helicity injection when there is little magnetic field emergence. |
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