Expositor: Yu Zhong (Department of Physics, University of Warwick)

Date: viernes 4 de octubre, 11:30 hs.

Abstract: Among the various magnetohydrodynamic (MHD) coronal wave phenomena, kink oscillations are particularly noteworthy for their potential roles in resolving several enigmatic problems of solar physics, such as coronal plasma heating, the physics of flares and coronal mass ejections, as well as for their use as natural diagnostic probes of the solar plasma through MHD seismology.

There are two regimes of kink oscillations, both of which have long been observed in TRACE, SDO/AIA, and SolO/EUI images. However, their drivers and damping mechanisms are still on debate. Decaying kink oscillations demonstrate large initial transverse displacements of coronal loops, typically excited by nearby low coronal eruptions. Their amplitudes rapidly decrease, influenced by linear or nonlinear damping mechanisms, such as resonant absorption and the Kelvin-Helmholtz instability. In contrast, the other regime, decayless kink oscillations, is characterized by low-amplitude displacements with no apparent decay, possibly sustained by self-oscillation mechanism or random motions at the footpoints. Their existence suggests a continuous supply of energy is required to counteract damping. Additionally, kink oscillations, as fast waves, were recently first observed converting to slow modes in the vicinity of a null point embedded in a solar pseudostreamer. In this talk, we will present recent work about the decaying-to-decayless transition and mode conversion of kink oscillations, as well as future perspectives.