分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： A GOES M1.9 flare took place in active region AR 11153 on February 9,2011. With the resolution of 200 kHz and a time cadence of 80 ms, the reverse-drifting (RS) type III bursts, intermittent sequence of type U bursts, drifting pulsation structure (DPS), and fine structures were observed by the Yunnan Observatories Solar Radio Spectrometer(YNSRS). Combined information revealed by the multi-wavelength data indicated that after the DPS which observed by YNSRS, the generation rate of type U bursts suddenly increased 5 times than before. In this event, the generation rate of type U bursts may depend on the magnetic reconnection rate. Our observations are consistent with previous numerical simulations results. After the first plasmoid produced (plasma instability occurred), the magnetic reconnection rate increased suddenly 5-8 times than before. Furthermore, after the DPS, the frequency range of turnover frequency of type U bursts is obviously broadened 3 times than before, which indicates the fluctuation amplitude of the density in the loop-top. Our observations also support the numerical simulations during the flare impulsive phase. The turbulence occurs at the top of the flare loop, the plasmoids can trap the non-thermal particles and cause the density fluctuation at the loop-top. The observations are generally consistent with the results of numerical simulations, helping us to better understand the characteristics of the whole physical process of eruption.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Lei Lu
Li Feng
Alexander Warmuth
Astrid M. Veronig
Jing Huang
Siming Liu
Weiqun Gan
Zongjun Ning
Beili Ying
Guannan Gao
摘要： Magnetic reconnection is a fundamental physical process converting magnetic energy into not only plasma energy but also particle energy in various astrophysical phenomena. In this letter, we show a unique dataset of a solar flare where various plasmoids were formed by a continually stretched current sheet. EUV images captured reconnection inflows, outflows, and particularly the recurring plasma blobs (plasmoids). X-ray images reveal nonthermal emission sources at the lower end of the current sheet, presumably as large plasmoids with a sufficiently amount of energetic electrons trapped in. In the radio domain, an upward slowly drifting pulsation structure, followed by a rare pair of oppositely drifting structures, was observed. These structures are supposed to map the evolution of the primary and the secondary plasmoids formed in the current sheet. Our results on plasmoids at different locations and scales shed important light on the dynamics, plasma heating, particle acceleration, and transport processes in the turbulent current sheet and provide observational evidence for the cascading magnetic reconnection process.
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