Magnetic reconnection is one of the most fundamental magnetized plasma processes in solar atmosphere. The leading theories hold that current sheet acts as a necessary prerequisite for the initiation of magnetohydrodynamic (MHD) reconnection process. Thus, studying the formation and evolution process of the current sheet is crucial for understanding the nature of magnetic reconnection in the solar atmosphere.

However, direct and clear observations of small-scale current sheet formation forced by external deformation or perturbations have been rarely reported yet.

On July 8,The Astrophysical Journal published an observational result made by CHEN Hechao et al., a PhD student from Yunnan Observatories, Chinese Academy of Sciences, the paper makes us a better understanding of the small-scale current sheet formation in the solar atmosphere.

Via observing two small-scale reconnection events near solar active region 12494, the researchers investigate in detail the current sheet formations within two X-shaped magnetic configurations. Based on the multiwavelength imaging observations, the apparent thickness/length, temperature/emission of the current sheet regions and their reconnection rates are also carefully analyzed.

In particular, a chain of high-speed plasmoid ejections was detected along with a set of the reconnected field lines, implying the onset of tearing-mode instability inside its current sheet region.

"These observations not only provide compelling evidence that non-radial rotating motion of filaments can serve as external flows to drive magnetic reconnection, but also give us a basic scenario of current sheet formation within small-scale magnetic reconnection processes”, CHEN Hechao said.

Contact:

CHEN Hechao, Yunnan Observatories, CAS

chc@ynao.ac.cn