SPATIAL SEISMOLOGY OF A LARGE CORONAL LOOP ARCADE FROMTRACEAND EIT OBSERVATIONS OF ITS TRANSVERSE OSCILLATIONS

Aims. The aim of this study is to investigate the excitation of kink oscillations in coronal loops and filaments, by analyzing a C3.4 circular-ribbon flare associated with a blowout jet in active region 12434 on 2015 October 16. Methods. The flare was observed in ultraviolet and extreme-ultraviolet wavelengths by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO) spacecraft. The line-of-sight (LOS) magnetograms of the photosphere were observed by the Helioseismic and Magnetic Imager on board SDO. Soft X-ray fluxes of the flares in 0.5−4 and 1−8 Å were recorded by the GOES spacecraft. Results. The flare excited small-amplitude kink oscillation of a remote coronal loop. The oscillation lasted for ≥4 cycles without significant damping. The amplitude and period are 0.3 ± 0.1 Mm and 207 ± 12 s. Interestingly, the flare also excited transverse oscillation of a remote filament. The oscillation lasted for ∼3.5 cycles with decaying amplitudes. The initial amplitude is 1.7−2.2 Mm. The period and damping time are 437−475 s and 1142−1600 s. The starting times of simultaneous oscillations of coronal loop and filament were concurrent with the hard X-ray peak time. Though small in size and short in lifetime, the flare set off a chain reaction. It generated a bright secondary flare ribbon (SFR) in the chromosphere, remote brightening (RB) that was cospatial with the filament, and intermittent, jet-like flow propagating in the northeast direction. Conclusions. The loop oscillation is most probably excited by the flare-induced blast wave at a speed of ≥1300 km s−1. The excitation of the filament oscillation is more complicated. The blast wave triggers secondary magnetic reconnection far from the main flare, which not only heats the local plasma to higher temperatures (SFR and RB), but produces jet-like flow (i.e., reconnection outflow) as well. The filament is disturbed by the secondary magnetic reconnection and experiences transverse oscillation. These findings provide new insight into the excitation of transverse oscillations of coronal loops and filaments.

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Acoustic response to transverse oscillations in a solar coronal loop

Astronomy and Astrophysics ◽

10.1051/0004-6361/202141515 ◽

2021 ◽

Author(s):

S. J. White ◽

E. Verwichte

Keyword(s):

Coronal Loop ◽

Acoustic Response ◽

Transverse Oscillations ◽

Solar Coronal

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Coronal Loop Transverse Oscillations Excited by Different Driver Frequencies

The Astrophysical Journal ◽

10.3847/1538-4357/ab1848 ◽

2019 ◽

Vol 876 (2) ◽

pp. 100 ◽

Cited By ~ 4

Author(s):

Andrey Afanasyev ◽

Konstantinos Karampelas ◽

Tom Van Doorsselaere

Keyword(s):

Coronal Loop ◽

Transverse Oscillations

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Contribution of observed multi frequency spectrum of Alfvén waves to coronal heating

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834158 ◽

2019 ◽

Vol 623 ◽

pp. A37 ◽

Cited By ~ 9

Author(s):

P. Pagano ◽

I. De Moortel

Keyword(s):

Active Region ◽

Power Spectrum ◽

Solar Corona ◽

Coronal Loop ◽

Alfven Waves ◽

Mhd Waves ◽

Alfvén Waves ◽

Coronal Loops ◽

Phase Mixing ◽

Transverse Oscillations

Context. Whilst there are observational indications that transverse magnetohydrodynamic (MHD) waves carry enough energy to maintain the thermal structure of the solar corona, it is not clear whether such energy can be efficiently and effectively converted into heating. Phase-mixing of Alfvén waves is considered a candidate mechanism, as it can develop transverse gradient where magnetic energy can be converted into thermal energy. However, phase-mixing is a process that crucially depends on the amplitude and period of the transverse oscillations, and only recently have we obtained a complete measurement of the power spectrum for transverse oscillations in the corona. Aims. We aim to investigate the heating generated by phase-mixing of transverse oscillations triggered by buffeting of a coronal loop that follows from the observed coronal power spectrum as well as the impact of these persistent oscillations on the structure of coronal loops. Methods. We considered a 3D MHD model of an active region coronal loop and we perturbed its footpoints with a 2D horizontal driver that represents a random buffeting motion of the loop footpoints. Our driver was composed of 1000 pulses superimposed to generate the observed power spectrum. Results. We find that the heating supply from the observed power spectrum in the solar corona through phase-mixing is not sufficient to maintain the million-degree active region solar corona. We also find that the development of Kelvin–Helmholtz instabilities could be a common phenomenon in coronal loops that could affect their apparent life time. Conclusions. This study concludes that is unlikely that phase-mixing of Alfvén waves resulting from an observed power spectrum of transverse coronal loop oscillations can heat the active region solar corona. However, transverse waves could play an important role in the development of small scale structures.

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