Apr 08, 2019
Based mainly on the high-resolution data obtained by the 1 meter New Vacuum Solar Telescope (NVST) at the Fuxian Solar Observatory, a small-scale oscillatory magnetic reconnection and the associated formation and disappearance of a solar flux rope in the solar chromosphere was reported for the first time by Dr. XUE Zhike's group at Yunnan Observatories of Chinese Academy of Sciences. The study was published in The Astrophysical Journal Letters.
Magnetic reconnection is an important physical process in astrophysics, and is the rearrangement of magnetic field topology. On the Sun, many erupting activities are associated with magnetic reconnections. However, the observations of small-scale magnetic reconnections, especially oscillatory magnetic reconnection, are rarely reported due to the resolutions of the observing equipment. So far, oscillatory reconnection is studied in numerical simulation.
In this study, the small-scale oscillatory magnetic reconnection occurred in the active region 11800 from July 24 to 25, 2013, and it consists of four relatively independent magnetic reconnections which last for about 48, 158, 275, and 340 minutes, respectively. Therefore, the oscillatory reconnection experiences two cycles, and the periods of the two oscillations are 206 and 615 minutes, respectively, which are much longer than the previous results.
Moreover, researchers found that the inflow/outflow regions of the previous magnetic reconnection are transformed into the outflow/inflow regions of the following magnetic reconnection. One current sheet was observed in each magnetic reconnection, and that four current sheets along two nearly perpendicular directions are formed alternately.
In addition, they observed that a small-scale flux rope forms and disappears during the oscillatory reconnection and its twist increases with the reconnection and transfers from the reconnection site to one leg. This led the flux rope to become more slender.
Researchers concluded that the formation and disappearance of the flux rope are caused by the oscillatory magnetic reconnection.
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