Formation of an Intermediate Filament Driven by Small-scale Magnetic Reconnection

We present the formation process of a filament in NOAA active region 12765 from 2020 June 5 to 8, using observations from the New Vacuum Solar Telescope, the Solar Dynamics Observatory, and the Global Oscillation Network Group. We found that intermittent small-scale magnetic reconnection occurs at the northern part of the filament, and the small-scale magnetic reconnection shows the characteristics of the oscillatory reconnections. During the magnetic reconnection process, a large amount of material is continuously injected into the filament channel. Furthermore, there are bidirectional inflow and outflow, current sheets, and bright cusp-shaped structures. The velocities of the material injections range from 17 to 183 km s(-1) with an average velocity of about 57 km s(-1). A total of 53 material injections were found from 03:10 UT on 2020 June 5 to 00:10 UT on June 8. The total mass carried by the injection events is about 7.39 x 10(14) g, and the total kinetic energy released through magnetic reconnection is approximately 3.09 x 10(21) J. The projection area of the filament increased from less than 1 x 10(2) Mm(2) to around 7 x 10(2) Mm(2). We conclude that the filament is formed by direct material injection into the filament channel due to the small-scale magnetic reconnections.

Automated summary

In this study, observations from the New Vacuum Solar Telescope, the Solar Dynamics Observatory, and the Global Oscillation Network Group were used to investigate the formation process of a filament in NOAA active region 12765 from June 5 to 8, 2020. It was found that intermittent small-scale magnetic reconnection occurred at the northern part of the filament, showing characteristics of oscillatory reconnections. The reconnection process resulted in continuous material injections into the filament channel, with bidirectional inflow and outflow, current sheets, and bright cusp-shaped structures. The formation of the filament was attributed to direct material injection into the filament channel due to small-scale magnetic reconnections.