Short period fast waves in solar coronal loops

Cooper, Fenwick; Nakariakov, V. M.; Williams, David R.

doi:10.1051/0004-6361:20031071

Cited by 93 publications

(79 citation statements)

References 17 publications

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“…The phase speed was about 2000 km s −1 . It was shown that the observed variation in the emission intensity was consistent with the modulation of the observed column depth of the loop by a kink wave (Cooper et al 2003). Propagating transverse waves were Article published by EDP Sciences investigated by Tomczyk et al (2007) in the visible light with the COMP instrument.…”

Section: Introductionsupporting

confidence: 55%

Propagating transverse waves in soft X-ray coronal jets

Farahani¹,

Doorsselaere²,

Verwichte³

et al. 2009

A&A

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Aims. The theoretical model for magnetohydrodynamic (MHD) modes guided by a field-aligned plasma cylinder with a steady flow is adapted to interpret transverse waves observed in solar coronal hot jets, discovered with Hinode/XRT in terms of fast magnetoacoustic kink modes. Methods. Dispersion relations for linear magnetoacoustic perturbations of a plasma jet of constant cross-section surrounded by static magnetised plasma are used to determine the phase and group speeds of guided transverse waves and their relationship with the physical parameters of the jet and the background plasma. The structure of the perturbations in the macroscopic parameters of the plasma inside and outside the jet, and the phase relations between them are also established. Results. We obtained a convenient expansion for the long wave-length limit of the phase and group speeds and have shown that transverse waves observed in soft-X-ray solar coronal jets are adequately described in terms of fast magnetoacoustic kink modes by a magnetic cylinder model, which includes the effect of a steady flow. In the observationally determined range of parameters, the waves are not found to be subject to either the Kelvin-Helmholtz instability or the negative energy wave instability, and hence they are likely to be excited at the source of the jet.

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Section: Introductionsupporting

confidence: 55%

Propagating transverse waves in soft X-ray coronal jets

Farahani¹,

Doorsselaere²,

Verwichte³

et al. 2009

A&A

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“…Murawski & Roberts 1993a,b). For the developed stage of the evolution the quasi-periodic wave trains are best described using wavelet analysis (Nakariakov et al 2004), which reveals the "crazy tadpole" characteristic signature also seen in data for propagating fast wave trains detected with the Solar Eclipse Coronal Imaging System (SECIS; Katsiyannis et al 2003;Cooper et al 2003) and in decimetric band radio bursts A&A 569, A12 (2014) (e.g. Mészárosová et al 2009aMészárosová et al ,b, 2011Mészárosová et al , 2013Karlický et al 2011Karlický et al , 2013.…”

Section: Introductionmentioning

confidence: 90%

Observation of a high-quality quasi-periodic rapidly propagating wave train using SDO/AIA

Nisticò

Pascoe

Nakariakov

2014

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Context. We present a new event of quasi-periodic wave trains observed in EUV wavebands that rapidly propagate away from an active region after a flare. Aims. We measured the parameters of a wave train observed on 7 December 2013 after an M1.2 flare, such as the phase speeds, periods and wavelengths, in relationship to the local coronal environment and the energy sources. Methods. We compared our observations with a numerical simulation of fast magnetoacoustic waves that undergo dispersive evolution and leakage in a coronal loop embedded in a potential magnetic field. Results. The wave train is observed to propagate as several arc-shaped intensity disturbances for almost half an hour, with a speed greater than 1000 km s −1 and a period of about 1 min. The wave train followed two different patterns of propagation, in accordance with the magnetic structure of the active region. The oscillatory signal is found to be of high-quality, i.e. there is a large number (10 or more) of subsequent wave fronts observed. The observations are found to be consistent with the numerical simulation of a fast wave train generated by a localised impulsive energy release. Conclusions. Transverse structuring in the corona can efficiently create and guide high-quality quasi-periodic propagating fast wave trains.

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“…However, the high temperatures and densities of flaring loops also lead to the increase in the plasma-β inside the loops (Shibasaki 2001). This can cause a significant deviation of the resonant periods and cut-offs from the results obtained in the zero-β approximation studied in Cooper et al (2003); Pascoe et al (2007b).…”

Section: Introductionmentioning

confidence: 94%

“…where k is the wavenumber and the phase speed C p = ω/k is in the range C A0 < C p < C Ae (Cooper et al 2003). Since C p is typically a large fraction of C Ae (for trapped modes) λ is usually of order 1.…”

Section: Sausage Modes In a Magnetic Slabmentioning

confidence: 99%

Characteristics of magnetoacoustic sausage modes

Inglis¹,

Doorsselaere²,

Brady³

et al. 2009

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Aims. We perform an advanced study of the fast magnetoacoustic sausage oscillations of coronal loops in the context of MHD coronal seismology to establish the dependence of the sausage mode period and cut-off wavenumber on the plasma-β of the loopfilling plasma. A parametric study of the ratios for different harmonics of the mode is also carried out. Methods. Full magnetohydrodynamic numerical simulations were performed using Lare2d, simulating hot, dense loops in a magnetic slab environment. The symmetric Epstein profile and a simple step-function profile were both used to model the density structure of the simulated loops. Analytical expressions for the cut-off wavenumber and the harmonic ratio between the second longitudinal harmonic and the fundamental were also examined. Results. It was established that the period of the global sausage mode is only very weakly dependent on the value of the plasma-β inside a coronal loop, which justifies the application of this model to hot flaring loops. The cut-off wavenumber k c for the global mode was found to be dependent on both internal and external values of the plasma-β, again only weakly. By far the most important factor in this case was the value of the density contrast ratio between the loop and the surroundings. Finally, the deviation of the harmonic ratio P 1 /2P 2 from the ideal non-dispersive case was shown to be considerable at low k, again strongly dependent on plasma density. Quantifying the behaviour of the cut-off wavenumber and the harmonic ratio has significant applications to the field of coronal seismology.

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Short period fast waves in solar coronal loops

Cited by 93 publications

References 17 publications

Propagating transverse waves in soft X-ray coronal jets

Propagating transverse waves in soft X-ray coronal jets

Observation of a high-quality quasi-periodic rapidly propagating wave train using SDO/AIA

Characteristics of magnetoacoustic sausage modes

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