Nonlinear Mode Conversion from a Large-amplitude Propagating Kink Wave to Longitudinal Oscillations in a Quiescent Prominence

Abstract In this Letter, we present the direct observations of a mode conversion from a large-amplitude transverse propagating kink wave to antiphase large-amplitude longitudinal oscillations (LALOs) in a quiescent prominence observed on 2014 February 25. This event was simultaneously recorded by the Solar Dynamics Observatory/Atmospheric Imaging Assembly and the Behind Solar Terrestrial Relation Observatory/Extreme Ultraviolet Imager. The transverse oscillation was triggered when a global extreme-ultraviolet wave associated with an X4.9 flare swept over the northern end of the prominence. For the first time, a clearly visible, coherent large-amplitude propagating kink wave was observed in the prominence, traveling southward along the prominence spine with a phase speed of ∼380 km s −1 . The propagating wave reached its largest initial amplitude (∼15 Mm) and period (∼24 minutes) near the spine center. After one cycle of the transverse oscillation, antiphase LALOs were detected simultaneously near both ends of the prominence, exhibiting similar physical parameters (period ∼79 minutes, initial displacement amplitude ∼10 Mm, and velocity amplitude ∼12 km s −1 ). Their strict antiphase relation, supported by quantitative order-of-magnitude consistency, demonstrates that the LALOs were directly triggered by a nonlinear magnetic pressure gradient (ponderomotive effect) induced by the large-amplitude propagating kink wave. These results provide the first direct evidence of the large-amplitude transverse-to-longitudinal wave-mode conversion and reveal the nonlinear coupling mechanism in a prominence.