Successive bursts in a complex magnetic configuration

CRISTIANI, G.D.; GIMéNEZ DE CASTRO, C.G.; MANDRINI, C.H.; ROVIRA, M.G.; KAUFMANN, P.

Mérida

Congreso; VIII Conferencia Latinoamericana de Geofísca Espacial (VIII COLAGE); 2007

Asociación Latinoamericana de Geofísca Espacial

We report for the first time an M class flare that shows a different submillimeter radio spectral component from the microwave classical burst. Two successive bursts of 2 min duration and separated by 2 min occurred in active region NOAA 10226, starting around 13:15 UT. Submillimeter flux density measured by the Solar Submillimeter Telescope (SST) is used, in addition to microwave total Sun patrol telescope observations. Images with Há filters, from the Há Solar Telescope for Argentina (HASTA), and extreme UV observations, from the Extreme-ultraviolet Imaging Telescope (EIT) aboard the Solar and Heliospheric Observatory (SoHO), are used to characterize the flaring region. An extensive analysis of the magnetic topology evolution is derived from the Michelson Doppler Imager (SoHO, MDI) magnetograms and used to constrain the solution space of the possible emission mechanisms.  The submillimeter component is only observed at 212 GHz.  The analysis of the magnetic topology reveals a very compact and complex system of arches that reconnects at low heights, while from the soft X-ray observations we deduce that the flaring area is dense. Accordingly, we conclude that the microwave emission comes from mildly relativistic electrons spiraling down along the reconnected loops.