The properties of solar radio spikes with harmonics and the associated EUV brightenings
Solar radio spikes are narrowband, short duration radio bursts. They are excited by the energetic electrons accelerated during small scale magnetic reconnections. Spikes play an important role in diagnosing magnetic reconnections and studying electron accelerations. In this paper, the solar radio spikes observed by the Chashan Solar Observatory (CSO) spectrograph combined with observations from the Solar Dynamics Observatory (SDO) are used to study the properties of spikes with harmonics. The CSO data show that the central frequency ratio of the third to the second harmonic is \(1.35 \pm 0.01\) and the third harmonic has a larger absolute and relative bandwidth, but a shorter duration than the second one. By studying the correlation between light curves of the solar radio spike and those of bright points at different Extreme UltraViolet (EUV) passbands, the best associated EUV bright point and passbands are determined. The spike source properties are discussed based on the extrapolated magnetic field around the associated EUV bright point.
KeywordsRadio bursts, meter-wavelengths and longer, spikes Radio emission, active regions Magnetic fields, corona
The authors gratefully acknowledge the teams of SDO, RSTN and ORFEES for making their data available to us. This work was supported by grants NNSFC-CAS U1831101, NNSFC 41331068, 11790303 (11790300), 11873036, and NSF of Shandong Province ZR201702100072.
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