Transverse Oscillation of Coronal Loops Induced by Eruptions of a Magnetic Flux Tube and a Plasmoid

We studied transverse oscillations in hot coronal loops of active region NOAA 12673 located at the west limb. Loop oscillations were associated with a plasmoid ejection from the same location. During the rising phase of the plasmoid, a magnetic flux tube was seen to be rising and bending towards the loop system that erupted before the plasmoid ejection. In addition to the plasmoid ejection, a large coronal mass ejection (CME) and an X8.2 flare were observed in the same active region for several hours ( ≈ 7 hours). After the plasmoid ejection, a follow-up shock wave from the flare site was triggered by a sudden momentum transfer towards the solar disk. It was found to be propagating across the entire solar disk with an average speed of ≈ 1290 km s − 1 . By analyzing the time sequence of these events, we found that a plasmoid ejection perturbed the loops from their equilibrium and set them in oscillation. We found different oscillations of the fundamental mode in two loops, fast decaying (with a period of 7.93 minutes and an average damping time of ≈ 19 minutes) and slow decaying (with a period of 6.31 minutes and an average damping time of ≈ 34 minutes). The two different oscillations could be due to their lengths, magnetic fields, and plasma densities. Using the methods of coronal seismology, we estimated the average magnetic field in the coronal loops to be 29 G and 36 G, which is consistent with the order of the coronal magnetic fields found in other studies.