# Untwisting and Disintegration of a Solar Filament Associated with Photospheric Flux Cancellation

## TL;DR

This study uses high-resolution solar observations to analyze the untwisting and disintegration of a solar filament, linking flux cancellation and magnetic field interactions to filament eruption mechanisms.

## Contribution

It provides detailed observational evidence supporting the flux cancellation model for filament eruptions, including measurements of twist, rotation, and magnetic field behavior.

## Key findings

- Filament exhibited an average unwinding rotation of ~10.5 degrees per minute.
- Estimated total twist before eruption was ~1.3 pi, below kink instability threshold.
- Flux cancellation and sheared magnetic fields played a key role in filament destabilization.

## Abstract

Using the high-resolution observations from New Vacuum Solar Telescope (NVST) jointly with the Solar Dynamics Observatory data, we investigate two successive confined eruptions (Erup1 and Erup2) of a small filament in a decaying active region on 2017 November 10. During the process of Erup1, the overlying magnetic arcade is observed to inflate with the rising filament at beginning and then stop the ongoing of the explosion. In the hot EUV channel, a coronal sigmoidal structure appears during the first eruption and fade away after the second one. The untwisting rotation and disintegration of the filament in Erup2 are clearly revealed by the NVST H_alpha intensity data, hinting at a pre-existing twisted configuration of the filament. By tracking two rotating features in the filament, the average rotational angular velocity of the unwinding filament is found to be ~10.5 degree/min. A total twist of ~1.3 pi is estimated to be stored in the filament before the eruption, which is far below the criteria for kink instability. In the course of several hours prior to the event, some photospheric flux activities, including the flux convergence and cancellation, are detected around the northern end of the filament, where some small-scale EUV brightenings are also captured. Moreover, strongly-sheared transverse fields are found in the cancelling magnetic features from the vector magnetograms. Our observational results support the flux cancellation model, in which the interaction between the converging and sheared opposite-polarity fluxes destabilizes the filament and triggers the ensuing ejection.