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A. Lara, N. Gopalswamy (The Catholic University of America)
We present a study of one active region with high flare and CME activity. From April 27 to May 5, 1998, AR8210 was crossing the south solar hemisphere and produced many flares, and at least five CMEs were related to activity in this region, some of them were homologous events.
We use magnetograms from the Michelson Doppler Imager (MDI) experiment on board of the Solar Heliospheric Observatory (SOHO) to construct the time series of the photospheric magnetic elements. We compute the line of sight magnetic flux over the entire active region, and over localized areas inside the active region in which activity was detected in EUV (198 Å) maps from the Extreme ultraviolet Imaging Telescope (EIT) on board of SOHO.
We found considerable differences between the positive and negative fluxes computed over the entire region, the mean negative flux per pixel was 50 to 100 % greater than the positive flux. Using microwave polarization measures from Nobeyama Radio Heliograph, we were able to confirm such differences. The magnetic flux computed over AR8210 also showed a considerable increasing phase when the flare and CME activity of the region was increasing. On the other hand, we found that in general, flares occur during a maximum phase in the magnetic flux computed over localized subregions and that the major changes on this magnetic flux seems to be related to CMEs.
Finally we discuss the flare and CME production, with special emphasis in the homologous events.