Helical eruptive prominence associated with a pair of overlapping CMEs on 21 April 2001

Abstract

The eruption of limb prominence on 21 April 2001 associated with two coronal mass ejections (CMEs) is investigated. Hα images reveal two large-scale eruptions (a promi- nence body and a southern foot-point arch), both showing helical internal structure. These two eruptions are found to be spatially and temporally associated with the corresponding CMEs. The kinematics and the study of geometrical parameters of the prominence show that the eruption was quite impulsive (with peak acceleration ≈470 m s−² ) and has taken place for relatively low pitch angle of helical threads, not exceeding tan θ ≈ 1.2. The stability criteria of the prominence are revisited in the light of the model of Vršnak (1990, Solar Phys. 129, 295) and the analysis shows that the eruption violates the instability criteria of that model. Finally, the energy stored in the prominence circuit and the energies (kinetic, potential, and magnetic) of the associated CMEs are estimated and it is found that there was enough energy stored in the prominence to drive the two CMEs.