An Analytical Model of the Kelvin–Helmholtz Instability of Transverse Coronal Loop Oscillations
Mihai Barbulescu,Michael S. Ruderman,Michael S. Ruderman,Tom Van Doorsselaere,Robert Erdélyi,Robert Erdélyi +5 more
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In this article, it was shown that the magnetic field at one side of the interface is inclined, which explains the numerically found fact that magnetic twist does not prevent the onset of the Kelvin-Helmholtz (KH) instability at the boundary of an oscillating magnetic tube.Abstract:
Recent numerical simulations have demonstrated that transverse coronal loop oscillations are susceptible to the Kelvin-Helmholtz (KH) instability due to the counter-streaming motions at the loop boundary. We present the first analytical model of this phenomenon. The region at the loop boundary where the shearing motions are greatest is treated as a straight interface separating time-periodic counter-streaming flows. In order to consider a twisted tube, the magnetic field at one side of the interface is inclined. We show that the evolution of the displacement at the interface is governed by Mathieu's equation and we use this equation to study the stability of the interface. We prove that the interface is always unstable, and that, under certain conditions, the magnetic shear may reduce the instability growth rate. The result, that the magnetic shear cannot stabilise the interface, explains the numerically found fact that the magnetic twist does not prevent the onset of the KH instability at the boundary of an oscillating magnetic tube. We also introduce the notion of the loop $\sigma$-stability. We say that a transversally oscillating loop is $\sigma$-stable if the KH instability growth time is larger than the damping time of the kink oscillation. We show that even relatively weakly twisted loops are $\sigma$-stable.read more
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Coronal heating by MHD waves
Tom Van Doorsselaere,Abhishek K. Srivastava,Patrick Antolin,Norbert Magyar,Soheil Vasheghani Farahani,Hui Tian,Hui Tian,Dmitrii Y. Kolotkov,Dmitrii Y. Kolotkov,Leon Ofman,Leon Ofman,Mingzhe Guo,Mingzhe Guo,Iñigo Arregui,Iñigo Arregui,Ineke De Moortel,Ineke De Moortel,D. J. Pascoe +17 more
TL;DR: In this article, the authors focus on recent advances in the understanding of MHD wave heating mechanisms in the solar corona and give an overview of observational results, where they show that different wave modes have been discovered in the corona in the last decade, many of which are associated with a significant energy flux, either generated in situ or pumped from the lower solar atmosphere.
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Amplitudes and Energy Fluxes of Simulated Decayless Kink Oscillations
TL;DR: In this paper, the authors investigate the correlation between the observed amplitudes of the oscillations and input the energy flux from different drivers, and find that low amplitude decayless kink oscillations may correspond to significant energy fluxes of the order of the radiative losses for the Quiet Sun.
Journal ArticleDOI
Coronal Heating by MHD Waves
Tom Van Doorsselaere,Abhishek K. Srivastava,Patrick Antolin,Norbert Magyar,Soheil Vasheghani Farahani,Hui Tian,Hui Tian,Dmitrii Y. Kolotkov,Dmitrii Y. Kolotkov,Leon Ofman,Leon Ofman,Mingzhe Guo,Mingzhe Guo,Iñigo Arregui,Iñigo Arregui,Ineke De Moortel,Ineke De Moortel,D. J. Pascoe +17 more
TL;DR: In this paper, the authors focus on recent advances in the understanding of MHD wave heating mechanisms in the solar corona and give an overview of observational results, where they show that different wave modes have been discovered in the corona in the last decade, many of which are associated with a significant energy flux, either generated in situ or pumped from the lower solar atmosphere.
Journal ArticleDOI
Coronal Loop Transverse Oscillations Excited by Different Driver Frequencies
TL;DR: In this paper, the authors analyze transverse oscillations of a coronal loop excited by continuous monoperiodic motions of the loop footpoint at different frequencies in the presence of gravity.
References
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TRACE observation of damped coronal loop oscillations: implications for coronal heating
TL;DR: The imaging telescope on board the Transition Region and Coronal Explorer spacecraft observed the decaying transversal oscillations of a long and thin coronal loop in the 171 angstrom Fe(IX) emission line, finding the coronal dissipation coefficient to be eight to nine orders of magnitude larger than the theoretically predicted classical value.
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Coronal Loop Oscillations Observed with the Transition Region and Coronal Explorer
TL;DR: In this article, spatial oscillations of coronal loops were detected in extreme-ultraviolet wavelengths (171 with the T ransition Region and Coronal Explorer, in the tem- Ae ) perature range of MK.
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The Damping of Coronal Loop Oscillations
Michael S. Ruderman,B. Roberts +1 more
TL;DR: In this paper, the authors show that a coronal flux tube with inhomogeneities on a small scale (confined to within a thin layer of order a�=! k in thickness) is able to support coherent oscillations for any length of time and so be observable.
Journal ArticleDOI
Coronal loop oscillations - An interpretation in terms of resonant absorption of quasi-mode kink oscillations
TL;DR: In this paper, the authors used the theoretical expressions for the decay time by Hollweg & Yang and Ruderman & Roberts to estimate the ratio of the length scale of inhomogeneity compared to the loop radius for a collection of loop oscillations.