Heating and Cooling in Transversely Oscillating Coronal Loops Powered by Broadband, Multi-Directional Wave Drivers

Howson, Thomas; Moortel, I. De

doi:10.3390/physics5010011

Cited by 5 publications

(3 citation statements)

References 72 publications

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“…To achieve an efficient energy flux, a driver with an eigenfrequency is a common choice. However, from a more realistic perspective, the use of a broadband driver has been discussed, for instance, by Afanasyev et al (2019), Pagano et al (2020), Howson & De Moortel (2023). In this case, the resonant component of the broadband driver can be selected by the loop, thus facilitating efficient energy injection.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Estimating the energy flux of transverse waves associated with Kelvin-Helmholtz instability in solar coronal loops

Guo¹,

Gao²,

Doorsselaere³

et al. 2023

A&A

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Context. The energy flux of kink waves in coronal loops has been estimated in previous studies. Recent numerical simulations have revealed that kink oscillations can induce a Kelvin-Helmholtz Instability (KHI) in magnetic flux tubes. This non-linear process breaks the assumptions that have typically been included in previous eigenmode analyses. Therefore, the current analytical expressions of energy flux need to be re-examined. Aims. In the present work, we aim to compare our numerical energy flux with previous analytical formulae and establish modifications to the estimation of the energy flux of kink waves in coronal loops. Methods. Working within the framework of ideal magnetohydrodynamics (MHD), we conducted three-dimensional (3D) simulations of kink oscillations in coronal cylinders. Forward models were also employed to translate our numerical results into observables using the FoMo code. Results. We find that the previous estimation of the energy flux of kink waves is reasonable up to the point before the KHI is fully developed. However, as small vortices develop, the energy flux derived from the analytical formula becomes smaller than the total Poynting flux calculated from our numerical results. Furthermore, when degrading the original numerical resolution to match a realistic instrumental resolution, for instance, the Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter (SO), the energy flux becomes much smaller than the numerical value. Conclusions. The energy flux calculated from the analytical formula should be modified by multiplying it by a factor of about 2. When it comes to the energy flux estimation based on SO/EUI observations, this factor should be between about 3 and 4.

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Section: Discussion and Concluding Remarksmentioning

confidence: 99%

Estimating the energy flux of transverse waves associated with Kelvin-Helmholtz instability in solar coronal loops

Guo¹,

Gao²,

Doorsselaere³

et al. 2023

A&A

View full text Add to dashboard Cite

show abstract

“…Many observations show that an enhanced power occurs at ∼3 mHz in the coronal velocity power spectrum, implying that the observed transverse waves may be excited by p-modes (e.g., Van Doorsselaere et al 2008;Tomczyk & McIntosh 2009;Morton et al 2015Morton et al , 2016Morton et al , 2019. Such a power spectrum has also been used to drive kink oscillations in simulated coronal loops (e.g., Pagano & De Moortel 2019;Howson & De Moortel 2023). Meanwhile, wave excitation by p-modes is also widely studied in a number of analytical and modeling works.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Transverse Oscillations Driven by p-modes in Short Coronal Loops

Gao 高,

Guo,

Van Doorsselaere

et al. 2023

ApJ

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Recent observations have revealed two types of decayless transverse oscillations in short coronal loops: one with short periods scaling with loop lengths, and the other with longer periods that exhibit a peak at around 5 minutes in the period distribution. To understand such a difference in period, we work in the framework of ideal MHD and model a short coronal loop embedded in an atmosphere with density stratification from the chromosphere to the corona. An inclined p-mode-like driver with a period of 5 minutes is launched at one loop footpoint. It is discovered that two types of decayless transverse oscillations can be excited in the loop. We interpret the 5 minutes periodicity as being directly driven by the footpoint driver, while the others, with periods of several tens of seconds, are regarded as kink eigenmodes of different harmonics. Therefore, our simulation shows that both types of decayless oscillations found in observations can be excited by p-modes in one short coronal loop. This study extends our understanding of ubiquitous decayless transverse oscillations in the corona. Furthermore, it suggests that p-modes could be an important energy source for coronal heating by driving decayless transverse oscillations.

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“…The contribution of footpoint-driven transverse waves with a multi-frequency spectrum in the energy evolution and heating of 3D coronal loops has also been studied in recent years (e.g. Pagano & De Moortel 2019;Pagano et al 2020;Howson & De Moortel 2023). However, no numerical study of 3D coronal loops perturbed by broadband drivers has reported on the excitation and evolution, spatial and temporal, of standing waves matching the observed decayless oscillations, in the presence or absence of a transition region and a lower chromosphere.…”

Section: Introductionmentioning

confidence: 99%

Decayless oscillations in 3D coronal loops excited by a power-law driver

Karampelas,

Van Doorsselaere

2023

A&A

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Aims. We studied the manifestation of decayless oscillations in 3D simulations of coronal loops, driven by random motions. Methods. Using the PLUTO code, we ran magnetohydrodynamic (MHD) simulations of a straight gravitationally stratified flux tube, with its footpoints embedded in chromospheric plasma. We consider transverse waves drivers with a horizontally polarised red noise power-law spectrum. Results. Our broadband drivers lead to the excitation of standing waves with frequencies equal to the fundamental standing kink mode and its harmonics. These standing kink oscillations have non-decaying amplitudes, and spectra that depend on the characteristics of the loops, with the latter amplifying the resonant frequencies from the drivers. We thus report for the first time in 3D simulations the manifestation of decayless oscillations from broadband drivers. The spatial and temporal evolution of our oscillation spectra reveals the manifestation of a half harmonic, which exhibits half the frequency of the identified fundamental mode with a similar spatial profile. Our results suggest that this mode is related to the presence of the transition region in our model and could be interpreted as being the equivalent to the fundamental mode of standing sound waves driven on pipes closed at one end. Conclusions. The potential existence of this half harmonic has important implications for coronal seismology, since misinterpreting it for the fundamental mode of the system can lead to false estimations of the average kink speed profile along oscillating loops. Finally, its detection could potentially give us a tool for distinguishing between different excitation and driving mechanisms of decayless oscillations in observations.

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Heating and Cooling in Transversely Oscillating Coronal Loops Powered by Broadband, Multi-Directional Wave Drivers

Cited by 5 publications

References 72 publications

Estimating the energy flux of transverse waves associated with Kelvin-Helmholtz instability in solar coronal loops

Estimating the energy flux of transverse waves associated with Kelvin-Helmholtz instability in solar coronal loops

Modeling of Transverse Oscillations Driven by p-modes in Short Coronal Loops

Decayless oscillations in 3D coronal loops excited by a power-law driver

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