Spatial damping of propagating kink waves due to mode coupling

Pascoe, D. J.; Hood, A. W.; Moortel, I. De; Wright, Andrew N.

doi:10.1051/0004-6361/201117979

Cited by 115 publications

(121 citation statements)

References 21 publications

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“…Hence the oscillation amplitude is described by a kind of Gaussian profile for small time and by the exponential function for larger time. This result is similar to one found by Pascoe et al (2010Pascoe et al ( , 2011Pascoe et al ( , 2012 for propagating waves. The dashed line in (30) we obtain t dc /Π = 4(π 2 κ) −1 .…”

Section: Examination Of Figs 1-3 Reveals That the Solution Can Be Wrsupporting

confidence: 91%

“…In particular, it was shown with the use of connection formulae that in the linear approximation the waves damp exponentially with the distance from the driver, and the damping length has been calculated. The same problem has been studied numerically by Pascoe et al (2010Pascoe et al ( , 2011Pascoe et al ( , 2012. In particular, Pascoe et al (2012) have shown that the wave amplitude does not decay exponentially everywhere.…”

Section: Introductionmentioning

confidence: 95%

“…The same problem has been studied numerically by Pascoe et al (2010Pascoe et al ( , 2011Pascoe et al ( , 2012. In particular, Pascoe et al (2012) have shown that the wave amplitude does not decay exponentially everywhere. At distances of the order of a few wave lengths, the amplitude dependence on the distance is described by the Gaussian profile.…”

Section: Introductionmentioning

confidence: 95%

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Damping of coronal loop kink oscillations due to mode conversion

Рудерман

Terradas

2013

A&A

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The damping of kink oscillations of a thin magnetic tube due to mode conversion, also called resonant absorption, is studied. The tube consists of a homogeneous core region and an inhomogeneous annulus, where the density monotonically decreases from its value in the core region to the value in the surrounding plasma. The annulus is assumed to be thin, so the study is carried out in the thin tube thin boundary approximation. The equation governing the amplitude variation of kink oscillations is derived. The initial value problem for this equation is solved to study the resonant damping. This means that, in particular, we study the transient state before the loop oscillates with the stationary or nearly stationary state. The results are compared with those of the direct numerical modelling, and the agreement is found to be fairly good. On the basis of the solution to the initial value problem for the governing equation, the damping time is calculated and compared with that given by the classical theory of resonant absorption. It is found that the classical theory underestimates the damping time, with the error increasing with the increase of the annulus thickness. However, the error is not large, so the damping time given by the classical theory of resonant absorption can be taken as a sufficiently good approximation.

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Section: Examination Of Figs 1-3 Reveals That the Solution Can Be Wrsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 95%

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Damping of coronal loop kink oscillations due to mode conversion

Рудерман

Terradas

2013

A&A

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“…Cross-correlation suggests the waves are propagating, implying an that initial increase in amplitude could be due to decreasing density with height. We speculate that the reduction in amplitude with height could be explained by spatial damping, e.g., by invoking resonant absorption as a damping mechanism for the transverse waves Pascoe et al 2012). Verth et al (2010) showed that resonant absorption is compatible with the decrease in propagating wave amplitude along coronal loops observed in CoMP (Tomczyk & McIntosh 2009).…”

Section: Discussionmentioning

confidence: 82%

Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions

Morton

McLaughlin

2013

A&A

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The recent launch of the High resolution Coronal imager (Hi-C) provided a unique opportunity of studying the EUV corona with unprecedented spatial resolution. We utilize these observations to investigate the properties of low-frequency (50−200 s) active region transverse waves, whose omnipresence had been suggested previously. The five-fold improvement in spatial resolution over SDO/AIA reveals coronal loops with widths 150−310 km and that these loops support transverse waves with displacement amplitudes <50 km. However, the results suggest that wave activity in the coronal loops is of low energy, with typical velocity amplitudes <3 km s −1 . An extended time-series of SDO data suggests that low-energy wave behaviour is typical of the coronal structures both before and after the Hi-C observations.

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“…Also, Reference 1 1 261 870 168 A02 2 265 300 72 3 316 500 174 4 277 400 204 5 272 849 162 6 435 600 258 7 143 200 166 8 423 800 406 9 185 200 192 10 396 400 Eq. (2) does not describe any transient behaviour in the damping (Pascoe et al 2012). Equation (2) shows that the resonant absorption time-scale scales linearly with period.…”

Section: Statistics Of Transverse Loop Oscillationsmentioning

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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Spatial damping of propagating kink waves due to mode coupling

Cited by 115 publications

References 21 publications

Damping of coronal loop kink oscillations due to mode conversion

Damping of coronal loop kink oscillations due to mode conversion

Hi-C and AIA observations of transverse magnetohydrodynamic waves in active regions

Statistical seismology of transverse waves in the solar corona

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