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Предвспышечные флуктуации радиоизлучения Солнца по наблюдениям на RSTN и NoRH
A number of solar flare events are analyzed using multi-frequency observations from the RSTN radio telescope network. Some events observed at the RSTN Learmonth station are compared with observations from the Nobeyama radioheliograph. The goal of the analysis was to identify precursors to solar flares. Pre-flare quasi-periodic fluctuations (PQF) in radio emission were detected in all the cases considered. The duration of pre-flare trains is 6–20 minutes. The trains consist of 3–5 pulses. PQF at lower frequencies (200–600 MHz) begin 2–6 minutes later than at high frequencies. PQF at frequencies of 2695–8800 MHz occur almost synchronously. The highest PQF amplitude is observed at a frequency of 4995 MHz. The observed CPFs can be explained by the force-free magnetic rope model (Solov’ev A.A., Kirichek E.A., 2023). According to this model, before the flare, during which a large amount of energy is released in the entire volume of the magnetic loop, plasma instability can occur several times in a narrow layer. Due to the small volume of this layer, a small amount of energy is released each time, which is noticeable only in the radio range. This manifests itself as repeating radio bursts before the flare.
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