An analysis of changes in the magnetic field of active region 9415 after the 2001 April 6 Solar Flare
Federated Physics Department of NJIT and Rutgers-Newark
Master of Science
Gary, Dale E.
The objective of this study was to further the current understanding of the correlation between solar flares and magnetic flux change. The average gradient of the magnetic flux around the neutral line of Active Region 9415 and the locations of the magnetic flux centers-of-mass in both polarities in AR 9415 were determined. Subsequent to the 2001 April 6 flare, there was a statistically significant mean increase of 0.00208 G/km in the average gradient. Prior to the flare, the magnetic flux centers-of-mass became increasingly sheared along the neutral line. After the flare, this shear suddenly decreased and the magnetic flux centers-of-mass converged towards the neutral line.
Presently, solar flares are believed to result when an active region relaxes towards the potential field configuration, i.e., the minimum energy state. Hence, magnetic shear, a measure of non-potentiality, is expected to decrease after a flare. If in fact magnetic gradient is proportional to magnetic shear, the increase in the average gradient implies that the magnetic shear around the neutral line increased following the flare. However, the sudden decrease in the magnetic flux center-of-mass separation parallel to the neutral line indicates an overall decrease in the magnetic shear of the whole active region. Therefore, it can be concluded that the magnetic shear kept increasing in local areas in spite of an overall decrease on the large scale subsequent to the flare. The local increase of magnetic shear in the neutral line region is believed to be associated with the convergence of magnetic fluxes in both polarities towards the neutral line.
njit-etd2005-121 (49 pages ~ 3,331 KB pdf)
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Created September 8, 2008