MHD seismology of coronal loops using the period and damping  of quasi-mode
 kink oscillations

Arregui, I.; Andries, Jesse; Doorsselaere, Tom Van; Goossens, Marcel; Poedts, Stefaan

doi:10.1051/0004-6361:20065863

Cited by 151 publications

(197 citation statements)

References 24 publications

(33 reference statements)

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“…At this point we like to stress that the TTTB approximation turns out to be remarkably accurate far beyond its domain of applicability. This is clearly illustrated in a recent analytical seismological study by Goossens et al (2008) which complemented a fully numerical seismology investigation by Arregui et al (2007). The eigenfunctions in the thin dissipative layer can be described by the functions F(τ) and G(τ) defined by for the driven problem and the functionsF(τ) and G(τ) defined by Ruderman et al (1995) for the incompressible eigenvalue problem and by Tirry & Goossens (1996) for the compressible eigenvalue problem.…”

Section: Pressureless Flux Tubes With Non-uniform Densitymentioning

confidence: 89%

On the nature of kink MHD waves in magnetic flux tubes

Goossens¹,

Terradas²,

Andries³

et al. 2009

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Context. Magnetohydrodynamic (MHD) waves are often reported in the solar atmosphere and usually classified as slow, fast, or Alfvén. The possibility that these waves have mixed properties is often ignored. Aims. The goal of this work is to study and determine the nature of MHD kink waves. Methods. This is done by calculating the frequency, the damping rate and the eigenfunctions of MHD kink waves for three widely different MHD waves cases: a compressible pressure-less plasma, an incompressible plasma and a compressible plasma which allows for MHD radiation. Results. In all three cases the frequency and the damping rate are for practical purposes the same as they differ at most by terms proportional to (k z R) 2 . In the magnetic flux tube the kink waves are in all three cases, to a high degree of accuracy incompressible waves with negligible pressure perturbations and with mainly horizontal motions. The main restoring force of kink waves in the magnetised flux tube is the magnetic tension force. The total pressure gradient force cannot be neglected except when the frequency of the kink wave is equal or slightly differs from the local Alfvén frequency, i.e. in the resonant layer. Conclusions. Kink waves are very robust and do not care about the details of the MHD wave environment. The adjective fast is not the correct adjective to characterise kink waves. If an adjective is to be used it should be Alfvénic. However, it is better to realize that kink waves have mixed properties and cannot be put in one single box.

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Section: Pressureless Flux Tubes With Non-uniform Densitymentioning

confidence: 89%

On the nature of kink MHD waves in magnetic flux tubes

Goossens¹,

Terradas²,

Andries³

et al. 2009

A&A

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201

229

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“…By combining the theories for the propagation and damping of the transverse wave it is possible to constrain the unknown parameters in the problem (Verwichte et al 2006) self-consistently. However, for the resonant absorption damping model, the problem is under-determined and it is not possible to deduce both density contrast and the thickness of the inhomogeneity layer independently (Arregui et al 2007;Goossens et al 2008;Arregui & Asensio Ramos 2011). A&A 552, A138 (2013) Ofman & Aschwanden (2002) modelled the scaling relations, e.g.…”

Section: Introductionmentioning

confidence: 99%

Statistical seismology of transverse waves in the solar corona

Verwichte

Doorsselaere

White

et al. 2013

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Context. Observations show that transverse oscillations commonly occur in solar coronal loops. The rapid damping of these waves has been attributed to resonant absorption. The oscillation characteristics carries information of the structuring of the corona. However, self-consistent seismological methods that extract information from individual oscillations are limited because there are fewer observables than unknown parameters in the model, and the problem is underdetermined. Furthermore, it has been shown that one-to-one comparisons of the observed scaling of period and damping times with wave damping theories are misleading. Aims. We aim to investigate whether seismological information can be gained from the observed scaling laws in a statistical sense. Methods. A statistical approach is used whereby scaling laws are produced by forward modelling using distributions of values for key loop cross-sectional structuring parameters. We study two types of observations: 1) transverse loops oscillations as seen mainly with TRACE and SDO and 2) running transverse waves seen with the Coronal Multichannel Polarimeter (CoMP). Results. We demonstrate that the observed period-damping time scaling law does provide information about the physical damping mechanism, if observations are collected from as wide range of periods as possible and a comparison with theory is performed in a statistical sense. The distribution of the ratio of damping time over period, i.e. the quality factor, has been derived analytically and fitted to the observations. A minimum value for the quality factor of 0.65 has been found. From this, a constraint linking the ranges of possible values for the density contrast and inhomogeneity layer thickness is obtained for transverse loop oscillations. If the layer thickness is not constrained, then the density contrast is at most equal to 3. For transverse waves seen by CoMP, it is found that the ratio of maximum to minimum values for these two parameters has to be less than 2.06; i.e., the sampled values for the layer thickness and Alfvén travel time come from a relatively narrow distribution. Conclusions. Now that more and more transverse loop oscillations have been analysed, a statistical approach to coronal seismology becomes possible. Using the observed data cloud, we have found restrictions to the loop's density contrast and inhomogeneity layer thickness. Surprisingly, for running waves, narrow distributions for loop parameters have been found.

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“…Comprehensive reviews of coronal seismology can be found in De Moortel (2005), Nakariakov & Verwichte (2005) and Banerjee et al (2007). Coronal seismology has also been developed extensively through several theoretical studies (including Ofman 2007;Selwa et al 2007a;Taroyan et al 2007;Van Doorsselaere et al 2007;Wang et al 2007;Ofman & Wang 2008), in particular including the effects of curvature (Van Doorsselaere et al 2004;Gruszecki et al 2007), longitudinal density variations (Erdelyi & Verth 2007;Verth et al 2007;Pascoe et al 2009) and transverse structuring (Arregui et al 2007;Ballai 2007;Pascoe et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Impulsively generated oscillations in a 3D coronal loop

Pascoe¹,

Moortel²,

McLaughlin³

2009

A&A

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Aims. The effect of changing the attack angle for the interaction of a fast MHD wave with a 3D coronal loop is studied, to investigate to what extent the properties of the excited transverse kink mode oscillations of the loop depend on this angle. Methods. 3D numerical simulations are performed of the interaction of a fast MHD wave, generated by a pressure pulse, with a 3D coronal loop. The loop itself is modelled as a density enhancement (with a finite plasma beta) within a magnetic arcade. The initial pressure pulse has a width comparable to the loop diameter and is situated outside of the loop, at the same height as the loop apex. This height is kept fixed but the (horizontal) angle between the pressure pulse and the loop is varied. Results. We find that the global, transverse kink mode is efficiently excited for a range of attack angles and qualitatively in agreement with theoretical expectations. The period and damping time are found to be independent of the attack angle. For larger values of the attack angle, the global (longitudinal) slow wave is excited, whereas for intermediate values the second harmonic kink mode is also present.

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MHD seismology of coronal loops using the period and damping of quasi-mode kink oscillations

Cited by 151 publications

References 24 publications

On the nature of kink MHD waves in magnetic flux tubes

On the nature of kink MHD waves in magnetic flux tubes

Statistical seismology of transverse waves in the solar corona

Impulsively generated oscillations in a 3D coronal loop

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