Based mainly on the high-resolution data obtained by the 1 meter New Vacuum Solar Telescope (NVST) at the Fuxian Solar Observatory of Yunnan Observatories, Chinese Academy of Sciences (CAS), a small-scale oscillatory magnetic reconnection and the associated formation and disappearance of a solar flux rope in the solar chromosphere have been reported for the first time by Dr. XUE Zhike et al. from Yunnan observatories, CAS. The finding has been published recently in The Astrophysical Journal Letters.

Magnetic reconnection is an important physical process in astrophysics. It is the rearrangement of magnetic field topology, in which the magnetic energy is released into plasma kinetic energy, thermal energy and radiation energy.

On the Sun, many erupting activities are associated with magnetic reconnections, such as coronal mass ejections, flares, filament eruptions, jets, etc. 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, but a complete observation of oscillatory reconnection has not been reported before yet.

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, it is also 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 is observed in each magnetic reconnection. Four current sheets along two nearly perpendicular directions are formed alternately.

In addition, a small-scale flux rope is observed to form and disappear during the oscillatory reconnection. Its twist increases with the reconnection and transfers from the reconnection site to one leg, and this leads the flux rope to become slender. The researchers conclude that the formation and disappearance of the flux rope are caused by the oscillatory magnetic reconnection.

Contact
XUE Zhike, YNAO, CAS
zkxue@ynao.ac.cn