Solar eruption activity is closely related to space disaster weather, dark bars are one of them. Recently, the reporter learned from the Yunnan Observatory of the Chinese Academy of Sciences that researchers at the Fuxian Lake Sun Observation and Research Base clearly observed that a small dark bar caused by asymmetric magnetic reconnection was cut off and erupted.
Dark bar (red arrow) and magnetic ring L1 asymmetric magnetic relink after the formation of magnetic ring Picture: Yunnan Observatory, Chinese Academy of Sciences
The sun’s dark bar is suspended in the high temperature, thin solar coronal atmosphere, and consists of relatively low temperature, high density plasma and correspondingly supported magnetic field structure, dark bar research has always been an important subject of solar physics. Magnetic reconnection is a physical process by two opposite sets of magnetic force lines close to each other and reconnected to form a new magnetic line, magnetic reconnection is a basic and very important physical process of rapid release of magnetic energy on the sun, solar explosion events almost all have a certain connection with magnetic reconnection, such as flares, dark bar bursts, coronal mass projectiles, jet streams and so on. Due to the limitation of the resolution of the observation equipment, there are still very few observational studies of small-scale magnetic relinking.
Xue Zhike, associate researcher of yunnan Observatory of the Chinese Academy of Sciences, researcher Yan Xiaoli and others mainly used high-resolution data from the one-meter new vacuum solar telescope at the Fuxian Lake Solar Observatory of the Yunnan Observatory, combined with the data of the solar dynamics observatory’s polar ultraviolet and vector magnetic field, and analyzed the complete process of small-scale asymmetric magnetic rejunction in the activity area of 12436 on October 23, 2015.
They found that, unlike the directional motion in the classical magnetic reconnection, the dark strip and the magnetic ring move in the same direction at the same time, followed by magnetic reconnection between them and the formation of a typical current, known as asymmetric magnetic reconnection, and finally the plasma is injected into the newly formed magnetic ring in the form of a rotating jet stream. In addition, it is also observed from the H-alpha Doppler image that the plasma in the magnetic reconnection area is redshifted throughout the magnetic reconnection process, which may be related to the magnetic topology.
This study is of great significance for the small-scale magnetic reconnection process and the formation and burst mechanism of the sun’s dark bars. The findings were published in the International Astronomical Journal of Astronomy and Astrophysics.