Why Do Torus-unstable Solar Filaments Experience Failed Eruptions?

Abstract

To investigate the factors that control the success and/or failure of solar eruptions, we study the magnetic field and 3-Dimensional (3D) configuration of 16 filament eruptions during 2010 July -2013 February. All these events, i.e., erupted but failed to be ejected to become a coronal mass ejection (CME), are failed eruptions with the filament maximum height exceeding 100M m. The magnetic field of filament source regions is approximated by a potential field extrapolation method. The filament 3D configuration is reconstructed from three vantage points by the observations of STEREO Ahead/Behind and SDO spacecraft. We calculate the decay index at the apex of these failed filaments and find that in 7 cases, their apex decay indexes exceed the theoretical threshold (n crit = 1.5) of the torus instability. We further determine the orientation change or rotation angle of each filament top during the eruption. Finally, the distribution of these events in the parameter space of rotation angle versus decay index is established. Four distinct regimes in the parameter space are empirically identified. We find that, all the torus-unstable cases (decay index n > 1.5), have a large rotation angles ranging from 50 • − 130 • . The possible mechanisms leading to the rotation and failed eruption are discussed. These results imply that, besides the torus instability, the rotation motion during the eruption may also play a significant role in solar eruptions.

Observations and 3D Magnetohydrodynamic Modeling of a Confined Helical Jet Launched by a Filament Eruption

“…Török & Kliem 2005b;Hassanin & Kliem 2016;Amari et al 2018;Liu et al 2018). In some cases the decay index may be high enough, but the development of the instability destroys the coherence of the flux rope before it can erupt (Zhou et al 2019). The kink instability is associated with the conversion of twist to the dimensionless quantity of writhe, i.e.…”

Mass of prominences experiencing failed eruptions

“…This rotation of the coronal field direction was not taken into account in many studies. On the other hand, Zhou et al (2019) relate the failure of filament eruptions with strong writhing motions during the eruptions with the rotation of the filament axis in the range of 50 • -130 • .…”

Magnetic Twists of Solar Filaments

“…Thus, similar to previous works (Zhou et al 2017(Zhou et al , 2019Guo et al 2019;Xu et al 2020), we can construct the three-dimensional filament geometry by the triangulation technique, and take it as the main axis of the MFR. The vector magnetic field is obtained by the Helioseismic and Magnetic Imager (HMI, Scherrer et al 2012;Schou et al 2012;Hoeksema et al 2014) on board SDO.…”

“…First, we need to construct the 3D path of the MFR axis. In the previous works (Zhou et al 2017(Zhou et al , 2019Guo et al 2019;Xu et al 2020), the triangulation method was adopted to construct the 3D path of the filament axis, which is taken as the MFR axis. However, this method does not work well for the low altitude parts of a filament.…”