Recently, Professor Cheng Xin and his team from the School of Astronomy and Space Sciences published a research paper titled “Ultra-high-resolution Observations of Persistent Null-point Reconnection in the Solar Corona” on Nature Communications (Nat Commun 2023 14, 2107, https://doi.org/10.1038/s41467-023-37888-w).

The abstract of the paper is as following:

Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, the research team presents ultra-high-resolution extreme ultraviolet observations of persistent null-point reconnection in the corona at a scale of about 390 km over one hour observations of the Extreme-Ultraviolet Imager on board Solar Orbiter spacecraft. The observations show formation of a null-point configuration above a minor positive polarity embedded within a region of dominant negative polarity near a sunspot. The gentle phase of the persistent null-point reconnection is evidenced by sustained point-like high-temperature plasma (about 10 MK) near the null-point and constant outflow blobs not only along the outer spine but also along the fan surface. The blobs appear at a higher frequency than previously observed with an average velocity of about 80 km s−1 and life-times of about 40 s. The null-point reconnection also occurs explosively but only for 4 minutes, its coupling with a mini-filament eruption generates a spiral jet. These results suggest that magnetic reconnection, at previously unresolved scales, proceeds continually in a gentle and/or explosive way to persistently transfer mass and energy to the overlying corona.

1. Based on the three-dimensional magnetic zero structure obtained by extrapolating the magnetic field of the photosphere, the gray curve forms a fan-shaped dome, and the convergence point in the middle is the magnetic zero point (red dot).

2. Point-like brightening produced by microscale magnetic zero reconnection near the active region in the extreme ultraviolet 174 Å band.

Translator: Shao Yihang

Editors: Guo Ankang, Shao Yihang