How Transverse Waves Drive Turbulence in the Solar Corona

Howson, Thomas

doi:10.3390/sym14020384

Cited by 4 publications

(5 citation statements)

References 159 publications

(201 reference statements)

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“…Due to the nature of the fundamental standing waves (perturbed velocities/ magnetic field largest at apex/footpoints), small scales in the velocity field tend to generate viscous heating at the loop apex, while small scales in the magnetic field typically produce ohmic heating at the loop footpoints (e.g., Karampelas et al 2017). A detailed review of the existing literature in this area is presented in Howson (2022).…”

Section: Introductionmentioning

confidence: 99%

(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?

Moortel

Howson

2022

ApJ

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Why the atmosphere of the Sun is orders of magnitudes hotter than its surface is a long standing question in solar physics. Over the years, many studies have looked at the potential role of magnetohydrodynamic (MHD) waves in sustaining these high temperatures. In this study, we use 3D MHD simulations to investigate (driven) transverse waves in a coronal loop. As the boundary-driven transverse waves propagate along the flux tube, the radial density profile leads to resonant absorption (or mode coupling) and phase mixing in the boundaries of the flux tube and the large velocity shears are subject to the Kelvin–Helmholtz instability (KHI). The combination of these effects leads to enhanced energy dissipation and wave heating. Considering both resonant and nonresonant boundary driving as well as different densities for the flux tube, we show that only wave heating associated with a resonant driver in a lower-density loop (with a loop core density ∼5 × 10−13 kg m−3) is able to balance radiative losses in the loop shell. Changing the model parameters to consider a denser loop or a driver with a nonresonant frequency, or both, leads to cooling of the coronal loop as the energy losses are greater than the energy injection and dissipation rates.

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Section: Introductionmentioning

confidence: 99%

(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?

Moortel

Howson

2022

ApJ

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“…We obtained a slightly increased value of α = 1.94 ± 0.009, compared with the original value of α. It is known that changes in energy flux are sensitive to the energy dissipation within the system (e.g., Klimchuk 2015;Prokopyszyn et al 2019;Howson 2022). However, before the full development of the energy cascading process, the growth of KHI is still closely related to numerical resistivity (e.g., Guo et al 2019a).…”

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

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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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“…The Multi-Slit Solar Explorer (MUSE) mission, due to launch in 2027, aims to deliver the high spatial resolution and temporal cadence necessary to understand the physical mechanisms of coronal heating (De Pontieu et al 2020, 2022Cheung et al 2022). MUSE will consist of a multi-slit extreme-ultraviolet (EUV) spectrograph and context imager.…”

Section: Muse Synthetic Emissionmentioning

confidence: 99%

“…Despite extensive research, it remains unclear whether magnetohydrodynamic (MHD) waves contribute significantly to coronal heating (see e.g. Parnell & De Moortel 2012;Arregui 2015;Van Doorsselaere et al 2020;Banerjee et al 2021;Howson 2022).…”

Section: Introductionmentioning

confidence: 99%

Identifying Alfvén wave modes in the solar corona

Enerhaug,

Howson,

De Moortel

2024

A&A

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Oscillations are observed to be pervasive throughout the solar corona, but it remains challenging to positively identify different wave modes. Improving this identification would provide a powerful tool for investigating coronal wave heating and improving seismological inversions. We aim to establish whether theoretical methods used to identify magnetohydrodynamical wave modes in numerical simulations can be employed on observational datasets. We applied wave identifiers based on fundamental wave characteristics such as compressibility and direction of propagation to a fully 3D numerical simulation of a transversely oscillating coronal loop. The same wave identifiers were applied to the line-of-sight integrated synthetic emission derived from the numerical simulation data to investigate whether this method could feasibly be useful for observational studies. We established that for particular line(s) of sight and assumptions about the magnetic field, we can correctly identify the properties of the Alfv\'en mode in synthetic observations of a transversely oscillating loop. Under suitable conditions, there is a strong agreement between the simulation and synthetic emission results. For the first time, we have provided a proof of concept that this theoretically derived classification of magnetohydrodynamic wave modes can be applied to observational data.

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How Transverse Waves Drive Turbulence in the Solar Corona

Cited by 4 publications

References 159 publications

(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?

(When) Can Wave Heating Balance Optically Thin Radiative Losses in the Corona?

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

Identifying Alfvén wave modes in the solar corona

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