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[2.05] The Magnetic Field Evolution of AR 10486 and AR 10488 Before and After the X17 Flare on Oct. 28, 2003

S. Regnier, B. Fleck (ESA/ESTEC)

We investigate the causes and the consequences of the X17 flare which occured in active region (AR) 10486 on Oct. 28, 2003. Using MDI high-cadence longitudinal magnetograms, we first follow the evolution of the photospheric magnetic field of both AR 10486 (site of the flare) and AR 10488 (new emerged active region). We then identify the main photospheric motions in AR 10486 which are precursors of the eruptive phenomena (e.g., emergence of flux, cancellation of flux). We also focus our study on the fast emergence of AR 10488 and the change of connectivity between the two active regions after the flare.

We also study the evolution of the coronal magnetic fields assuming a potential field equilibrium state. This is a case study to know if we can forecast a solar eruption using a time series of potential field extrapolations.

For both active regions, an IVM vector magnetogram is available almost 16 hours before the flare and is used as a snapshot. Those two magnetograms allow us to determine the nonlinear force-free magnetic configurations as well as the free energy budgets. These computations allow us to estimate how far those active regions are from the potential field configurations.

S. Regnier's research is funded by the European Community's Human Potential Programme through the European Solar Magnetism Network (contract HPRN-CT-2002-00313).

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Bulletin of the American Astronomical Society, 36 #2
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