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| Paper: |
Variations of Current Helicity in Active Region 10930 as Inferred from Hinode Spectropolarimeter Data and Cancellation Exponent |
| Volume: |
454, The 3rd Hinode Science Meeting |
| Page: |
311 |
| Authors: |
Yurchyshyn, V.; Abramenko, V.; Watanabe, H. |
| Abstract: |
Current helicity derived from vector magnetograms possesses a well-pronounced
scaling behavior, which can be studied by introducing a signed measure and
calculating the power-law exponent (cancellation exponent).
The time variations of this exponent seem to be related to flare activity of
an active region. Here we focus on changes of current helicity
in active region NOAA 10930 as derived from a set of Hinode spectropolarimeter
data. Our findings are that the cancellation exponent
first strongly increased on Dec 11 then rapidly decreased after a small
sunspot-satellite developed. Afterward, the cancellation exponent began
its gradual increase without significant new magnetic flux emergence.
These two different modes of behavior may indicate different processes
that ultimately led to an eruption: the first process is rapid injection
of current helicity, while the second process is gradual redistribution
of injected helicity over all spatial scales in the active region. |
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