Probing the twist angle of confined prominence eruption using SDO/AIA data

Abstract

In this context, we utilized a simplified representation of the curved cylinder flux tube to approximate the helical structure of the prominence. By considering the bright helical features as indicators of the magnetic field, we measured the average twist angle of the prominence legs. To gather the necessary data, we obtained image data with a wavelength of 171 Å from the Solar Dynamic Observatory (SDO)/Advanced Imaging Assembly (AIA) archive. We employed some IDL routines within the SolarSoft (SSW) package to determine the flux rope’s total twist angle for a confined prominence eruption. Specifically, we focus on a confined prominence eruption that occurred at the south-east limb of the Sun for an active region (AR) NOAA (AR 11 117) observed on October 21, 2010. The eruption commenced on 2010-10-21 at 21:56:18 UT and lasted until 2010-10-22 at 01:24:58 UT. During this event, a B2.6 flare class that occurred on 2010-10-21 at 23:17 UT, located at heliographic position of N20E84. Our results indicate that the distance between the two footpoints is up to 18 670 km. Initially, when the event began the height (h) was found to be 21 162.1 km, but the height was increased to reach 80 362.4 km at the end of eruption. The flux rope’s average twist angle (ϕ, in radian) at the beginning of eruption was ϕ = 13.4π. As the prominence ascended to higher levels, the twist angle was decreased gradually due to the magnetic field relaxation reached to ϕ = 3.6π. We determined that the flux ropes average twist angle (ϕ) that exceed the threshold for the helical kink instability. Therefore, we conclude that the eruption was caused by helical kink instability, as a result it is in consistent with other investigations.