The damping of slow MHD waves in solar coronal magnetic fields

Moortel, I. De; Hood, A. W.

doi:10.1051/0004-6361:20030984

Cited by 164 publications

(149 citation statements)

References 37 publications

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“…This damping rate is similar to that seen from the inclusion of non-ideal terms (e.g. Nakariakov et al 2000;Ofman & Wang 2002;De Moortel & Hood 2003). However, this damping is not due to the resistivity as the currents present during this stage of the simulation remain below the value required to trigger the resistivity.…”

Section: Resultssupporting

confidence: 81%

“…However, here the wave modes are established self consistently from the kink instability. From the studies of Nakariakov et al (2000), Ofman & Wang (2002) and De Moortel & Hood (2003) it was concluded that the dominant mechanism responsible for the damping of slow modes is thermal conduction. The 1D nature of the previous wave generation works allowed the straightforward inclusion of non-ideal thermal transport terms.…”

Section: Introductionmentioning

confidence: 99%

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Coronal loop slow mode oscillations driven by the kink instability

Haynes

Arber

Verwichte

2007

A&A

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Aims. To establish the dominant wave modes generated by an internal, m = 1 kink instability in a short coronal flux tube. Methods. The 3D MHD numerical simulations are performed using Lare3d to model the kink instability and the subsequent wave generation. The initial conditions are a straight, zero net current flux tube containing a twist higher than the kink instability threshold. Results. It is shown that the kink instability initially sets up a 1st harmonic (1st overtone) that is converted through the rearrangement of the magnetic field into two out-of-phase fundamental slow modes. These slow modes are in the two entwined flux tubes created during the kink instability. Conclusions. The long-lived oscillations established after a kink instability provide a possible way to identify whether sudden, short coronal loop brightenings may have resulted from a confined kink instability. The mode oscillation structure changes from the 1st harmonic to fundamental due to field line relaxation. The subsequent decay in the fundamental mode is comparable to observations and is caused by shock dissipation. This result has important consequences for the damping of the slow mode oscillations observed by SUMER.

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Coronal loop slow mode oscillations driven by the kink instability

Haynes

Arber

Verwichte

2007

A&A

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“…When k increases, t dl /P takes its minimum value, and then starts to grow (e.g. De Moortel & Hood 2003). However, we can still make a qualitative comparison.…”

Section: Nonlinear Damping Of Slow Wavesmentioning

confidence: 98%

Nonlinear damped standing slow waves in hot coronal magnetic loops

Ruderman

2013

A&A

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We study the nonlinear standing slow waves in coronal magnetic loops. We assume that the wave amplitude is sufficiently small and use it as a small parameter in the asymptotic expansions. In addition, we assume that the wave damping is sufficiently slow, which enables us to introduce the "slow" time related to the evolution of the wave amplitude and shape. We show that, in the leading-order approximation, the nonlinear standing wave is a superposition of two identical nonlinear waves propagating in the opposite directions. The two waves are governed by the Burgers equation. Using the Cole-Hopfe substitution, we obtain an analytical solution describing a standing wave that has the form of the linear fundamental eigenmode at the initial moment of time. This solution is used for the parametric study of nonlinear standing waves. In particular, the effect of nonlinearity on the oscillation damping time is investigated.

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“…The amplitude is observed to damp very quickly, typically within 2.9−23.3 Mm (1−2 visible wave fronts) along the wave path (De Moortel et al 2002b). Thermal conduction appears to be the dominant damping mechanism (De Moortel & Hood 2003;Ofman & Wang 2002;Klimchuk et al 2004). The energy flux carried by the EUV propagating disturbances was estimated to be far too insufficient to contribute significantly to coronal heating (Ofman et al 2000;De Moortel et al 2002b).…”

Section: Introductionmentioning

confidence: 99%

Measuring the apparent phase speed of propagating EUV disturbances

Yuan

Nakariakov

2012

A&A

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Context. Propagating disturbances of the EUV emission intensity are commonly observed over a variety of coronal structures. Parameters of these disturbances, particularly the observed apparent (image-plane projected) propagation speed, are important tools for MHD coronal seismology. Aims. We design and test tools to reliably measure the apparent phase speed of propagating disturbances in imaging data sets. Methods. We designed cross-fitting technique (CFT), 2D coupled fitting (DCF) and best similarity match (BSM) to measure the apparent phase speed of propagating EUV disturbances in the running differences of time-distance plots (R) and background-removed and normalised time-distance plots (D).Results. The methods were applied to the analysis of quasi-periodic EUV disturbances propagating at a coronal fan-structure of active region NOAA11330 on 27 Oct. 2011, observed with the Atmospheric Imaging Assembly (AIA) on SDO in the 171 Å bandpass. The noise propagation in the AIA image processing was estimated, resulting in the preliminary estimation of the uncertainties in the AIA image flux. This information was used in measuring the apparent phase speed of the propagating disturbances with the CFT, DCF and BSM methods, which gave consistent results. The average projected speed is measured at 47.6 ± 0.6 km s −1 and 49.0 ± 0.7 km s −1 for R and D, with the corresponding periods at 179.7 ± 0.2 s and 179.7 ± 0.3 s, respectively. We analysed the effects of the lag time and the detrending time in the running difference processing and the background-removed plot, on the measurement of the speed, and found that they are fairly weak. Conclusions. The CFT, DCF and BSM methods are found to be reliable techniques for measuring the apparent (projected) phase speed. The samples of larger effective spatial length are more suitable for these methods. Time-distance plots with background removal and normalisation allow for more robust measurements, with little effect of the choice of the detrending time. Cross-fitting technique provides reliable measurements on good samples (e.g. samples with large effective detection length and recurring features). 2D coupled-fitting is found to be sensitive to the initial guess for parameters of the 2D fitting function. Thus DCF is only optimised in measuring one of the parameters (the phase speed in our application), while the period is poorly measured. Best similarity measure is robust for all types of samples and very tolerant to image pre-processing and regularisation (smoothing).

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The damping of slow MHD waves in solar coronal magnetic fields

Cited by 164 publications

References 37 publications

Coronal loop slow mode oscillations driven by the kink instability

Coronal loop slow mode oscillations driven by the kink instability

Nonlinear damped standing slow waves in hot coronal magnetic loops

Measuring the apparent phase speed of propagating EUV disturbances

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