Small-scale motions in solar filaments as the precursors of eruptions

TL;DR

This study demonstrates that an increase in the standard deviation of line-of-sight velocities in solar filaments consistently precedes eruptions across various filament types, suggesting its potential as a predictive precursor.

Contribution

It extends previous findings by analyzing 12 filaments, confirming the standard deviation increase as a common precursor in different filament types.

Findings

Standard deviation of LOS velocities increases before filament eruptions.

Quiescent filaments show a longer duration of velocity standard deviation increase.

The velocity standard deviation can serve as an eruption precursor.

Abstract

Filaments, the dense cooler plasma floating in the solar corona supported by magnetic fields, generally exhibit certain activations before they erupt. In our previous study (Seki et al. 2017 ), we observed that the standard deviation of the line-of-sight (LOS) velocities of the small-scale motions in a filament increased prior to its eruption. However, because that study only analyzed one event, it is unclear whether such an increase in the standard deviation of LOS velocities is common in filament eruptions. In this study, 12 filaments that vanished in H{\alpha} line center images were analyzed in a manner similar to the one in our previous work; these included two quiescent filaments, four active region filaments, and six intermediate filaments. We verified that in all the 12 events, the standard deviation of the LOS velocities increased before the filaments vanished. Moreover, we observed that the quiescent filaments had approximately 10 times longer duration of an increase in the standard deviation than the other types of filaments. We concluded that the standard deviation of the LOS velocities of the small-scale motions in a filament can potentially be used as the precursor of a filament eruption.