Solar flares are impulsive releases of magnetic energy in the Sun’s atmosphere, producing broadband electromagnetic radiation from radio waves through optical and ultraviolet up to X- and gamma-ray photons. Their intensity is quantified by the peak soft X-ray flux in the range of 1 – 8 {\AA} as measured by the GOES satellites, and thus classified—on a logarithmic scale—into A, B, C, M, and X classes, each representing a tenfold increase in flux. Accurate forecasting of both the timing and intensity class of solar flares is essential for mitigating their potentially severe impacts. Among the most promising precursors are very-long-period pulsations (VLPs)—broadband oscillations with reported periods of roughly 8–30 minutes that typically emerge one to two hours before flare onset. In this study, we analyzed GOES 1–8 {\AA} soft X-ray data of three new flares and detected distinctive pre-flare VLP signatures in two M-class events. Measured pulsation periods detected are 25.2 and 20.0 (mixed with a period of 43 minutes), and each event exhibited four to six discrete pulses. Our analysis showed that increasing the number of free parameters in the fitting function can significantly enhance the accuracy of the flux model, as evidenced by improved goodness-of-fit metrics. The remaining third flare in our sample showed no clear VLP activity in the pre-eruption interval.
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Fathalian, N., & Jalalirad, M. (2025). Observational Insights into Pre-Flare Very Large Pulsations in the Solar Corona. Iranian Journal of Astronomy and Astrophysics, 12(1), 99-109. doi: 10.22128/ijaa.2025.2993.1217
MLA
Narges Fathalian; Malihe Jalalirad. "Observational Insights into Pre-Flare Very Large Pulsations in the Solar Corona", Iranian Journal of Astronomy and Astrophysics, 12, 1, 2025, 99-109. doi: 10.22128/ijaa.2025.2993.1217
HARVARD
Fathalian, N., Jalalirad, M. (2025). 'Observational Insights into Pre-Flare Very Large Pulsations in the Solar Corona', Iranian Journal of Astronomy and Astrophysics, 12(1), pp. 99-109. doi: 10.22128/ijaa.2025.2993.1217
VANCOUVER
Fathalian, N., Jalalirad, M. Observational Insights into Pre-Flare Very Large Pulsations in the Solar Corona. Iranian Journal of Astronomy and Astrophysics, 2025; 12(1): 99-109. doi: 10.22128/ijaa.2025.2993.1217
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