Multi-wavelength analysis of an M6.7 flare from AR10486

LUONI, M.L.; RAULIN, J.P; MANDRINI, C.H.; BANDEIRA, P.; DÉMOULIN, P.; KAUFMANN, P.; LUTHI, T.; GIMÉNEZ DE CASTRO, C.G.

Pucón

Congreso; 11th Latin-American Regional Meeting, IAU Meeting, (LARIM-2005); 2005

IAU

During October - November 2003 the most intense flares of the historyof Solar Physics were registered. Twelve X-class (X-ray GOESclassification) flares, including the strongest ever recorded (X28),originated from three beta-gamma-delta sunspot groups. Eight of theseflares started in the complex active region (AR) 10486 (NOAA number).These flares occured while AR 10486 maintained extreme size andcomplex magnetic structure in its transit across the visiblesolar disk.In this work, we concentrate in the study of the M6.7flare (12:27 UT) on October 27, 2003. We use data in differentwavelenghts provided by instruments observing from the photosphereto the corona, such as the: Michelson Doppler Imager (SoHO/MDI),H$\alpha$ Solar Telescope for Argentina (HASTA), Extreme UltravioletImaging Telescope (SoHO/EIT) and Submillimeter Solar Telescope (SST).The radio data were complemented by the patrol recordsof Bern Polarimeters, and the observations of Kosma and Bemrak.We analyze the magnetic field evolution and compute the coronalmagnetic field using MDI magnetograms as boundary condition. Fromthe model we find that a magnetic null point was present in thecorona. We propose that magnetic reconnection at thisnull point is responsible for the M6.7 flare. The radio flare showsa short impulsive phase ($\sim$ 1 minute) followed by a gradual($\sim$ 1 hour) emission, the latter being well associated with theH$\alpha$ time history. The radio spectrum during the impulsive peaksuggests the presence of energetic electrons radiating bysynchrotron. During the extended phase the radiospectrum is flat up to very high frequencies, indicating that theemission is due to the thermal radiation of cool and dense plasma.