Study of the excitation of large amplitude oscillations in a prominence by nearby flares

Abstract

Large amplitude oscillations commonly occur in solar prominences, triggered by energetic phenomena such as jets and flares. On March 14-15, 2015, a filament partially erupted in two stages, leading to oscillations in different parts. This study explores longitudinal oscillations from the eruption, focusing on the mechanisms behind their initiation, with special attention to the large oscillation on March 15. The oscillations and jets are analyzed using the time-distance technique. For flares and their interaction with the filament, we analyze AIA channels and use the DEM technique. Initially, a jet fragments the filament, splitting it into two segments. One remains in place, while the other detaches and moves. This causes oscillations in both segments: (a) the position change causes the detached segment to oscillate with a period of $69 \pm 3$ minutes; (b) the jet flows cause the remaining filament to oscillate with a period of $62 \pm 2$ minutes. In the second phase, on March 15, another jet seemingly activates the detached filament eruption, followed by a flare. A large longitudinal oscillation occurs in the remnant segment with a period of $72 \pm 2$ minutes and velocity amplitude $73 \pm 1 \, \mathrm{km s^{-1}}$. During the oscillation trigger, bright field lines connect the flare with the filament, appearing only in the AIA 131$\r{A}$ and 94$\r{A}$ channels, indicating the presence of hot plasma. DEM analysis confirms this, showing plasma around 10 MK pushing the prominence from its southeastern side, displacing it along the field lines and starting the oscillation. From this, the flare -- not the preceding jet-triggers the oscillation. The hot plasma flows into the filament channel. We explain how flares trigger large oscillations in filaments by proposing that post-flare loops reconnect with the filament channel's magnetic field.