Prominence Eruption Initiated by Helical Kink Instability of an Embedded Flux Rope

Abstract

We study the triggering mechanism of a limb-prominence eruption and the associated coronal mass ejection ( CME ) near AR 12342 using Solar Dynamics Observatory and Large Angle and Spectrometric Coronagraph / Solar Heliospheric Observatory observations. The prominence is seen with an embedded fl ux thread ( FT ) at one end and bifurcates from the middle to a different footpoint location. The morphological evolution of the FT is similar to that of an unstable fl ux rope ( FR ) , which we regard as a prominence-embedded FR. The FR twist exceeds the critical value. In addition, the morphology of the prominence plasma in 304 Å  images marks the helical nature of the magnetic skeleton, with a total of 2.96 turns along arc length. The potential fi eld extrapolation model indicates that the critical height of the background magnetic fi eld gradient falls within the inner corona ( 105 Mm ) , which is consistent with the extent of coronal plasma loops. These results suggest that the helical kink instability in the embedded FR caused the slow rise of the prominence to the height of the torus instability domain. Moreover, the differential emission measure analysis unveils heating of the prominence plasma to coronal temperatures during an eruption, suggesting reconnection-related heating underneath the upward rising embedded FR. The prominence starts with a slow rise motion of 10 km s − 1 , which is followed by fast and slow acceleration phases that have an average acceleration of 28.9 m s − 2 and 2.4 m s − 2 in C2 and C3 fi eld of view, respectively. As predicted by previous numerical simulations, the observed synchronous kinematic pro fi les of the CME leading edge and the core support the involved FR instability in the prominence initiation.