Dr. GAO Guannan from Yunnan Observatories of the Chinese Academy of Sciences and her co-authors reported recent study on the decimetric type-U solar radio bursts observed by Yunnan Observatories Solar Radio Spectrometer (YNSRS). They found that the generation rate of type-U solar radio bursts represented the magnetic reconnection rate in this event.
As far as they know, this is the first time to observe the change process of magnetic reconnection rate by solar radio bursts. They also studied a series of phenomena such as the density varies at the top of the flare loop, and the significant rise of the whole flare-loop system in their work. This work was published in The Astrophysical Journal a few days ago.
Magnetic reconnection is an important energy release process in the solar eruption, and is generally considered to be the main driving mechanism of solar eruptions, such as flares, Coronal Mass Ejections (CMEs) and jets. In the numerical experiments of magnetic reconnection, the magnetic reconnection rate is an important parameter. Based on Lin & Forbes (2000) solar eruption catastrophe model, Shen et al. (2011) and Ni et al (2018) found that the magnetic reconnection rate increases rapidly after the emergence of the first plasmoid, which is 5-8 times than before. However, it is difficult to detect these changes of magnetic reconnection rate in the observation, due to the poor resolution of observation and appropriate tracer.
The type-U bursts from YNSRS with the time and frequency resolutions are 80ms and 200kHz respectively. Combined with multi-band observation data, magnetic reconnection releases energy and drives the jet, togther with the plasmoid was found in the intermittent type-U bursts. The type U bursts are divided into type-U bursts before and after the plasmoid, and the generation rate of type-U bursts is about 5 times that before. This is consistent with the change of magnetic reconnection rate obtained in previous numerical experiments.
Contact:
GAO Guannan, Yunnan Observatories, CAS
ggn@ynao.ac.cn
