Sub-THz and Hα Activity during the Preflare and Main Phases of a GOES Class M2 Event
White, Stephen M.; Kaufmann, Pierre; Marcon, Rogério; Giménez de Castro, C. Guillermo; Raulin, Jean-Pierre; Correia, Emilia; Olavo Fernandes, Luis; de Souza, Rodney V.; Godoy, Rodolfo; Marun, Adolfo; Pereyra, Pablo
Brazil, United States, Argentina
Abstract
Radio and optical observations of the evolution of flare-associated phenomena have shown an initial and rapid burst at 0.4 THz only followed subsequently by a localized chromospheric heating producing an Hα brightening with later heating of the whole active region. A major instability occurred several minutes later producing one impulsive burst at microwaves only, associated with an M2.0 GOES X-ray flare that exhibited the main Hα brightening at the same site as the first flash.The possible association between long-enduring time profiles at soft X-rays, microwaves, Hα, and sub-THz wavelengths is discussed. In the decay phase, the Hα movie shows a disrupting magnetic arch structure ejecting dark, presumably chromospheric, material upward. The time sequence of events suggests genuine interdependent and possibly non-thermal instabilities triggering phenomena, with concurrent active region plasma heating and material ejection.