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[39.01] Magnetic Helicity Change Rate Associated With X-Class and M-Class Flares

K. Hartkorn, H. Wang, W. Cao, C. Denker, Y. Xu (New Jersey Institute of Technology)

We investigate the total helicity change rate of active regions during the time period of five X-class and five M-class flares. The X-class flares include the X17 flare on October 28 2003 and the X11 flare on October 29 2003. For the X11 flare we have high-resolution IR and G-band data available which allows us to compare flow fields derived from this high-resolution data with the flow fields derived from MDI full disc magnetograms.

Four out of five regions with X-class flares show a significant change in the helicity change rate, while none of the five active regions with an associated M-class flare shows this behavior. We determine the location of the helicity change in the active regions and discuss possible causes. We also investigate active regions with no flare activity to determine the fluctuations of the helicity change rate due to instrumental effects.

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Bulletin of the American Astronomical Society, 36 #2
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