Submillimeter Observations of an X1.2 Solar Flare

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

Pucón

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

IAU

We analyze the October 30, 2004, X1.2/SF event that occurred in active region (AR) 10691 (N13 W13) at 11:38 UT. High-time resolution flux density observations at 212 GHz obtained by the Solar Submillimeter Telescope (SST) show an intense (~1600 s.f.u.) impulsive burst followed by a long-lasting thermal phase. Emission above background level was also detected at 405 GHz (the second observational frequency of SST). We complement the spectral radio analysis with data from the Radio Solar Telescope Network (RSTN) in the range of 0.265 to 15.4 GHz with 1 second time resolution. EUV images from the Extreme Ultraviolet Imaging Telescope (EIT) are used to identify the possible emitting sources. Assuming that the origin of the emission during the impulsive phase is gyrosynchrotron radiation from mildly relativistic electrons, we derive the parameters of the accelerated electrons and emitting source using the gyrosynchrotron codes developed by Ramaty et al. (ApJ 436, 941, 1994). A good fit to the flux data can be achieved taking B=160-200 G, 0.15 Mev < E < Mev, delta=3.9 and a source size of 25´´. This size agrees with the one observed in EIT images. The long-lasting phase is analyzed in terms of thermal emission and compared with the radio flux inferred from the temperature and emission measure derived from the Geostationary Operational Environmental Satellites (GOES) data. The flux data shape closely follows the radio flux predicted from the soft X-ray data. Although the observed absolute flux density exceeds the predicted one by a factor 5, we argue that both come from a common source, having electron populations with different temperatures.