Propagating transverse waves in soft X-ray coronal jets

Farahani, S. Vasheghani; Doorsselaere, Tom Van; Verwichte, E.; Nakariakov, V. M.

doi:10.1051/0004-6361/200911840

Cited by 59 publications

(45 citation statements)

References 26 publications

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“…This is similar to the case of untwisted non-rotating tubes with equilibrium field-aligned steady flows, when the asymmetry is caused by the Doppler shift (e.g. Nakariakov et al 1996;Vasheghani Farahani et al 2009). In Eq.…”

Section: Casesupporting

confidence: 65%

Long-wavelength torsional modes of solar coronal plasma structures

Farahani¹,

Nakariakov²,

Doorsselaere³

2010

A&A

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Aims. We consider the effects of the magnetic twist and plasma rotation on the propagation of torsional m = 0 perturbations of cylindrical plasma structures (straight magnetic flux tubes) in the case when the wavelength is much longer than the cylinder diameter. Methods. The second order thin flux tube approximation is used to derive dispersion relations and phase relations in linear longwavelength axisymmetric magnetohydrodynamic waves in uniformly twisted and rotating plasma structures. Results. Asymptotic dispersion relations linking phase speeds with the plasma parameters are derived. When twist and rotation are both present, the phase speed of torsional waves depends upon the direction of the wave propagation, and also the waves are compressible. The phase relations show that in a torsional wave the density and azimuthal magnetic field perturbations are in phase with the axial magnetic field perturbations and anti-phase with tube cross-section perturbations. In a zero-β non-rotating plasma cylinder confined by the equilibrium twist, the density perturbation is found to be about 66 percent of the amplitude of the twist perturbation in torsional waves.

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Section: Casesupporting

confidence: 65%

Long-wavelength torsional modes of solar coronal plasma structures

Farahani¹,

Nakariakov²,

Doorsselaere³

2010

A&A

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“…An equivalent problem has been studied in the context of propagating transverse waves in coronal jets by Vasheghani Farahani et al (2009). These authors have also found that in the observationally determined range of parameters, the waves do not undergo either to the KHI or the negative energy wave instability.…”

Section: Basic Features: Uniform Tubementioning

confidence: 99%

The effect of longitudinal flow on resonantly damped kink oscillations

Terradas

Goossens

Ballai³

2010

A&A

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Context. The most promising mechanism acting towards damping the kink oscillations of coronal loops is resonant absorption. In this context most of previous studies neglected the effect of the obvious equilibrium flow along magnetic field lines. The flows are in general sub-Alfvénic and hence comparatively slow. Aims. Here we investigate the effect of an equilibrium flow on the resonant absorption of linear kink MHD waves in a cylindrical magnetic flux tube with the aim of determining the changes in the frequency of the forward and backward propagating waves and in the modification of the damping times due to the flow. Methods. A loop model with both the density and the longitudinal flow changing in the radial direction is considered. We use the thin tube thin boundary (TTTB) approximation in order to calculate the damping rates. The full resistive eigenvalue problem is also solved without assuming the TTTB approximation. Results. Using the low ratio of flow and Alfvén speeds we derive simple analytical expressions to the damping rate. The analytical expressions are in good agreement with the resistive eigenmode calculations. Conclusions. Under typical coronal conditions the effect of the flow on the damped kink oscillations is weak when the characteristic scale of the density layer is similar or lower than the characteristic width of the velocity layer. However, in the opposite situation the damping rates can be significantly altered, specially for the backward propagating wave which is undamped while the forward wave is overdamped.

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“…This discovery was later confirmed by McIntosh et al (2011) using imaging data of SDO/AIA. Hinode/XRT has also observed transverse waves in coronal jets (Cirtain et al 2007;Vasheghani Farahani et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

Doorsselaere

Gijsen

Andries

et al. 2014

ApJ

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In the last few years, it has been found that transverse waves are present at all times in coronal loops or spicules. Their energy has been estimated with an expression derived for bulk Alfvén waves in homogeneous media, with correspondingly uniform wave energy density and flux. The kink mode, however, is localized in space with the energy density and flux dependent on the position in the cross-sectional plane. The more relevant quantities for the kink mode are the integrals of the energy density and flux over the cross-sectional plane. The present paper provides an approximation to the energy propagated by kink modes in an ensemble of flux tubes by means of combining the analysis of single flux tube kink oscillations with a filling factor for the tube cross-sectional area. This finally allows one to compare the expressions for energy flux of Alfvén waves with an ensemble of kink waves. We find that the correction factor for the energy in kink waves, compared to the bulk Alfvén waves, is between f and 2f , where f is the density filling factor of the ensemble of flux tubes.

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Propagating transverse waves in soft X-ray coronal jets

Cited by 59 publications

References 26 publications

Long-wavelength torsional modes of solar coronal plasma structures

Long-wavelength torsional modes of solar coronal plasma structures

The effect of longitudinal flow on resonantly damped kink oscillations

Energy Propagation by Transverse Waves in Multiple Flux Tube Systems Using Filling Factors

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