Sub-THz and H{\alpha} activity during the preflare and main phases of a GOES class M2 event

TL;DR

This study investigates the sequence of radio, optical, and X-ray phenomena during a solar flare, revealing early sub-THz bursts, localized chromospheric heating, and magnetic ejections, highlighting complex interdependent instabilities.

Contribution

It provides new insights into the timing and association of multi-wavelength emissions and magnetic activity during a GOES M2 solar flare.

Findings

Early sub-THz burst precedes Hα brightening

Impulsive microwave burst correlates with main X-ray flare

Magnetic arch ejection observed during decay phase

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 H{\alpha} 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 H{\alpha} brightening at the same site as the first flash. The possible association between long-enduring time profiles at soft X-rays, microwaves, H{\alpha} and sub-THz wavelengths is discussed. In the decay phase the H{\alpha} movie shows a disrupting magnetic arch structure ejecting dark, presumably chromospheric, material upwards. The time sequence of events suggests genuine interdependent and possibly non-thermal instabilities triggering phenomena, with concurrent active region plasma heating and material ejection.