On 2022 February 2, Nature Communications published a collaborative work completed by researchers from Yunnan Observatories, Harbin Institute of Technology, University of Potsdam, University of St Andrews，National Astronomical Observatories, and National Space Science Center. Researchers find the formation of magnetic islands with the twisted structure in the current sheet during the fast magnetic reconnection for the first time.

Magnetic reconnection is an important process of energy release on the Sun, which transfers magnetic energy to heating, accelerating particles and radiation energy. It plays an important role in astronomy, space science, and laboratory plasma. However, the detailed process of magnetic reconnection is still not clear.

Using high temporal and spatial resolution observations of the New Vacuum Solar Telescope (NVST), combined with UV and EUV images, and vector magnetograms observed by SDO (Solar Dynamics Observatory), spectra from Hinode, as well as the X-ray data from RHESSI and GOES, scientists studied in detail the process of the magnetic reconnection during a confined solar flare in active region NOAA 11967 on 2014 February 02. They found that the magnetic reconnection occurred between a twisted magnetic flux rope enveloping a filament and magnetic loops rooting in the near chromospheric fibrils.

The most complete observational evidences of magnetic reconnection so far were observed in this event, including reconnection inflows and outflows, the newly formed magnetic loops, current sheet, hot cusp-shaped structures, downflows, and so on. The estimated reconnection rate ranges from 0.01 to 0.03, which belongs to fast magnetic reconnection. From EUV observations, they found that the plasmoids formed in the current sheet and moved to the two ends of the current sheet. By using vector magnetic fields from SDO/HMI, they also carried out the data-driven simulation. The results showed that plasmoids formed in the current sheet and confirmed that the plasmoids are the mini twisted flux ropes.

This research reveals the fine process of a fast magnetic reconnection, which makes people deepen the understanding of the basic process of magnetic reconnection. It is of great significance to study the physical characteristics and law of solar activities.

Moreover, this study provides an important guideline for eruptive activities in other objects (Sun-like stars, neutron stars, and black holes), magnetic dissipation in astronomy, space science and laboratory plasma.

Contact:

YAN Xiaoli, Yunnan Observatories, CAS
yanxl@ynao.ac.cn

The fine process of the fast magnetic reconnect revealed by the observations of NVST and SDO and data-driven simulation(Image by YAN Xiaoli etl)