The effect of density stratification on the resonant absorption of MHD waves in coronal loops

AbstractResonant absorption of MHD waves in coronal loops is studied in linear, viscous MHD. Viscosity is described by Braginskii’s viscosity stress tensor. The dependence of the process of resonant absorption on the viscosity coefficients is studied. The compressive viscosity and viscosity due to the finite Larmor radius do not produce absorption. Shear viscosity produces absorption and is a viable candidate for heating coronal loops. The width of the dissipation layer is found to be proportional to, whereη1is the shear viscous coefficient of the full viscous stress tensor.

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The Effect of Twisted Magnetic Field on the Resonant Absorption of MHD Waves in Coronal Loops

Solar Physics ◽

10.1007/s11207-010-9537-0 ◽

2010 ◽

Vol 263 (1-2) ◽

pp. 87-103 ◽

Cited By ~ 19

Author(s):

K. Karami ◽

K. Bahari

Keyword(s):

Magnetic Field ◽

Resonant Absorption ◽

Mhd Waves ◽

Coronal Loops

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Damping of magnetohydrodynamic waves by resonant absorption in the solar atmosphere

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2005.1708 ◽

2005 ◽

Vol 364 (1839) ◽

pp. 433-446 ◽

Cited By ~ 77

Author(s):

M Goossens ◽

J Andries ◽

I Arregui

Keyword(s):

Resonant Absorption ◽

Mhd Waves ◽

Coronal Loops ◽

Two Dimensional ◽

Heliospheric Observatory ◽

Magnetohydrodynamic Waves ◽

One Dimensional ◽

Magnetic Structures ◽

Different Types ◽

Kink Waves

In the last decade we have been overwhelmed by an avalanche of discoveries of magnetohydrodynamic (MHD) waves by the Solar and Heliospheric Observatory and Transition Region and Coronal Explorer observatories. Both standing and propagating versions of fast magnetoacoustic and slow magnetoacoustic MHD waves have been detected. Information on the damping times and damping distances of these waves is less detailed and less accurate than that on periods and amplitudes. Nevertheless, observations show the damping times and damping lengths are often short. Also, different types of MHD waves in different types of magnetic structures likely require different damping mechanisms. The phenomenon of fast damping is well documented for the standing fast magnetosonic kink waves in coronal loops. This paper concentrates on standing fast magnetosonic waves. It reports on results on periods and damping times due to resonant absorption in one-dimensional and two-dimensional models of coronal loops. Special attention is given to multiple modes.

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Seismology of kink oscillations in coronal loops: Two decades of resonant damping

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308014920 ◽

2007 ◽

Vol 3 (S247) ◽

pp. 228-242 ◽

Cited By ~ 7

Author(s):

Marcel Goossens

Keyword(s):

Wave Theory ◽

Resonant Absorption ◽

Mhd Waves ◽

Coronal Loops ◽

Equilibrium Models ◽

Kink Waves ◽

The Common ◽

Uniform Equilibrium ◽

Transverse Oscillations ◽

Alfven Velocity

AbstractThe detection of rapidly damped transverse oscillations in coronal loops by Aschwanden et al. (1999) and Nakariakov et al. (1999) gave a strong impetus to the study of MHD waves and their damping. The common interpretation of the observations of these oscillations is based on kink modes. This paper reviews how the observed period and damping time can be reproduced by MHD wave theory when non-uniform equilibrium models are considered that have a transversal variation of the local Alfven velocity. The key point here is that resonant absorption cannot be avoided and occurs as natural damping mechanism for kink waves in non-uniform equilibrium models. The present paper starts with work by Hollweg & Yang (1988) and discusses subsequent developments in theory and their applications to seismology of coronal loops. It addresses the consistent use of observations of periods and damping times as seismological tools within the framework of resonant absorption. It shows that within the framework of resonant absorption infinitely many equilibrium models can reproduce the observed values of periods and damping times.

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Linear Visco-Resistive Computations of Magnetohydrodynamic Waves: I. The Code and Test Cases

International Astronomical Union Colloquium ◽

10.1017/s0252921100025926 ◽

1994 ◽

Vol 144 ◽

pp. 503-505

Author(s):

R. Erdélyi ◽

M. Goossens ◽

S. Poedts

Keyword(s):

Resonant Absorption ◽

Numerical Code ◽

Mhd Waves ◽

Test Cases ◽

Numerical Accuracy ◽

Element Discretization ◽

Flux Tubes ◽

Magnetohydrodynamic Waves ◽

Viscosity Coefficients ◽

Magnetic Flux Tubes

AbstractThe stationary state of resonant absorption of linear, MHD waves in cylindrical magnetic flux tubes is studied in viscous, compressible MHD with a numerical code using finite element discretization. The full viscosity tensor with the five viscosity coefficients as given by Braginskii is included in the analysis. Our computations reproduce the absorption rates obtained by Lou in scalar viscous MHD and Goossens and Poedts in resistive MHD, which guarantee the numerical accuracy of the tensorial viscous MHD code.

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Resonant absorption of kink magnetohydrodynamic waves by a magnetic twist in coronal loops

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stw1677 ◽

2016 ◽

Vol 462 (1) ◽

pp. 1002-1011 ◽

Cited By ~ 7

Author(s):

Zanyar Ebrahimi ◽

Kayoomars Karami

Keyword(s):

Resonant Absorption ◽

Coronal Loops ◽

Magnetohydrodynamic Waves

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The Distinction Between Thermal Nonequilibrium and Thermal Instability

Solar Physics ◽

10.1007/s11207-019-1562-z ◽

2019 ◽

Vol 294 (12) ◽

Cited By ~ 5

Author(s):

James A. Klimchuk

Keyword(s):

Large Amplitude ◽

Thermal Instability ◽

Mhd Waves ◽

Accelerated Cooling ◽

Coronal Loops ◽

Thermal Nonequilibrium ◽

Cold Condensation

AbstractFor some forms of steady heating, coronal loops are in a state of thermal nonequilibrium and evolve in a manner that includes accelerated cooling, often resulting in the formation of a cold condensation. This is frequently confused with thermal instability, but the two are in fact fundamentally different. We explain the distinction and discuss situations where they may be interconnected. Large-amplitude perturbations, perhaps associated with MHD waves, likely play a role in explaining phenomena that have been attributed to thermal nonequilibrium but also seem to require cross-field communication.

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