The Evolution of Magnetic Rayleigh–Taylor Unstable Plumes and Hybrid KH-RT Instability into a Loop-like Eruptive Prominence

Abstract

MRT-unstable plumes are observed in a loop-like eruptive prominence using Solar Dynamic Observatory /Atmospheric Imaging Assembly observations. The small-scale cavities are developed within the prominence, where perturbations trigger dark plumes (P1 and P2) propagating with speeds of 35–46 km s −1 . The self-similar plume formation initially shows the growth of a linear MRT-unstable plume (P1), and thereafter the evolution of a nonlinear single-mode MRT-unstable second plume (P2). A differential emission measure analysis shows that plumes are less dense and hotter than the prominence. We have estimated the observational growth rate for both plumes as 1.32 ± 0.29 × 10 −3 s −1 and 1.48 ± 0.29 × 10 −3 s −1 , respectively, which are comparable to the estimated theoretical growth rate (1.95 × 10 −3 s −1 ). The nonlinear phase of an MRT-unstable plume (P2) may collapse via a Kelvin–Helmholtz vortex formation in the downfalling plasma. Later, a plasma thread is evident in the rising segment of this prominence. It may be associated with the tangled field and Rayleigh–Taylor instability. The tangled field initiates shearing at the prominence–cavity boundary. Due to this shear motion, the plasma downfall occurred at the right part of the prominence–cavity boundary. It triggers the characteristic KH unstable vortices and MRT-unstable plasma bubbles propagating at different speeds and merging with each other. The shear motion and lateral plasma downfall may initiate hybrid KH-RT instability there.