Excitation and evolution of vertically polarised transverse loop oscillations by coronal rain

Verwichte, E.; Kohutova, Petra

doi:10.1051/0004-6361/201730675

Cited by 24 publications

(14 citation statements)

References 28 publications

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“…The rain, emitting in chromospheric optical lines, allows a high resolution window into wave processes within the loops. Low amplitude kink oscillations are commonly seen in these structures (Verwichte and Kohutova 2017), including cases of amplification (Antolin and Verwichte 2011) or steady oscillations (Kohutova and Verwichte 2016).…”

Section: Kink Oscillations In Loops Undergoing Coolingmentioning

confidence: 99%

“…In large loop oscillations, the ponderomotive force could affect the phenomenon of the coronal rain (Verwichte et al 2017), but it is probably not the primary reason for the observed sub-ballistic motions of the plasma blobs (Antolin and Rouppe van der Voort 2012). The ponderomotive force could be a possible cause of the first ionisation potential (FIP) effect, related to the enhancement or depletion, respectively, in coronal abundance with respect to photospheric values of elements with FIP below about 10 eV (Laming 2015).…”

Section: Field-aligned Flows Driven By the Ponderomotive Force In Kink Wavesmentioning

confidence: 99%

“…Coronal rain consists of dense and cold plasma blobs guided along magnetic field lines and resulting from a process of thermal instability. Observations of a coronal loop collected on 27 August 2014 with IRIS, Hinode/SOT, and AIA showed that coronal rain, forming at the loop top by a process of catastrophic cooling, moved downwards along the loop in conjunction with small-amplitude, vertically polarised decayless kink oscillations (Verwichte and Kohutova 2017).…”

Section: Observations Of Decayless Oscillationsmentioning

confidence: 99%

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Kink Oscillations of Coronal Loops

et al. 2021

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Kink oscillations of coronal loops, i.e., standing kink waves, is one of the most studied dynamic phenomena in the solar corona. The oscillations are excited by impulsive energy releases, such as low coronal eruptions. Typical periods of the oscillations are from a few to several minutes, and are found to increase linearly with the increase in the major radius of the oscillating loops. It clearly demonstrates that kink oscillations are natural modes of the loops, and can be described as standing fast magnetoacoustic waves with the wavelength determined by the length of the loop. Kink oscillations are observed in two different regimes. In the rapidly decaying regime, the apparent displacement amplitude reaches several minor radii of the loop. The damping time which is about several oscillation periods decreases with the increase in the oscillation amplitude, suggesting a nonlinear nature of the damping. In the decayless regime, the amplitudes are smaller than a minor radius, and the driver is still debated. The review summarises major findings obtained during the last decade, and covers both observational and theoretical results. Observational results include creation and analysis of comprehensive catalogues of the oscillation events, and detection of kink oscillations with imaging and spectral instruments in the EUV and microwave bands. Theoretical results include various approaches to modelling in terms of the magnetohydrodynamic wave theory. Properties of kink oscillations are found to depend on parameters of the oscillating loop, such as the magnetic twist, stratification, steady flows, temperature variations and so on, which make kink oscillations a natural probe of these parameters by the method of magnetohydrodynamic seismology.

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Section: Kink Oscillations In Loops Undergoing Coolingmentioning

confidence: 99%

Section: Field-aligned Flows Driven By the Ponderomotive Force In Kink Wavesmentioning

confidence: 99%

Section: Observations Of Decayless Oscillationsmentioning

confidence: 99%

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Kink Oscillations of Coronal Loops

et al. 2021

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“…These MHD oscillations could be identified in the EUV/SXR imaging observations (Nakariakov et al, 1999;Aschwanden et al, 2002;Shen et al, 2013;Goddard & Nakariakov, 2016), and in the spectroscopic observations (Kliem et al, 2002;Mariska, 2005;Li et al, 2015a). The detected periods vary from a few seconds to minutes Schrijver et al, 2002;Tian et al, 2016;Verwichte & Kohutova, 2017).…”

Section: Introductionmentioning

confidence: 99%

Non-damping oscillations at flaring loops

Yuan

et al. 2018

A&A

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Context. Quasi-periodic oscillations are usually detected as spatial displacements of coronal loops in imaging observations or as periodic shifts of line properties (i.e., Doppler velocity, line width and intensity) in spectroscopic observations. They are often applied for remote diagnostics of magnetic fields and plasma properties on the Sun. Aims. We combine imaging and spectroscopic measurements of available space missions, and investigate the properties of nondamping oscillations at flaring loops. Methods. We used the Interface Region Imaging Spectrograph (IRIS) to measure the spectrum over a narrow slit. The doublecomponent Gaussian fitting method was used to extract the line profile of Fe xxi 1354.08 Å at the 'O i' spectral window. The quasiperiodicity of loop oscillations were identified in the Fourier and wavelet spectra. Results. A periodicity at about 40 s is detected in the line properties of Fe xxi 1354.08 Å, hard X-ray emissions in GOES 1−8 Å derivative, and Fermi 26−50 keV. The Doppler velocity and line width oscillate in phase, while a phase shift of about π/2 is detected between the Doppler velocity and peak intensity. The amplitudes of Doppler velocity and line width oscillation are about 2.2 km s −1 and 1.9 km s −1 , respectively, while peak intensity oscillate with amplitude at about 3.6% of the background emission. Meanwhile, a quasi-period of about 155 s is identified in the Doppler velocity and peak intensity of the Fe xxi 1354.08 Å line emission, and AIA 131 Å intensity. Conclusions. The oscillations at about 40 s are not damped significantly during the observation, it might be linked to the global kink modes of flaring loops. The periodicity at about 155 s is most likely a signature of recurring downflows after chromospheric evaporation along flaring loops. The magnetic field strengths of the flaring loops are estimated to be about 120−170 G using the MHD seismology diagnostics, which are consistent with the magnetic field modeling results using the flux rope insertion method.

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“…This includes the observation of transverse loop oscillations, which were first observed in connection with eruption events by TRACE (Aschwanden et al 1999;Nakariakov et al 1999) and are routinely observed since (e.g. Verwichte et al 2009;Van Doorsselaere et al 2008;White et al 2012a;Verwichte & Kohutova 2017). MHD wave theory reveals these oscillations to be fast magnetoacoustic in nature that exhibit periodic coherent displacements of the loop axis in a quasi-incompressible manner (Edwin & Roberts 1983;Nakariakov & Ofman 2001;Aschwanden et al 2002;Verwichte et al 2004).…”

Section: Introductionmentioning

confidence: 98%

Acoustic response to transverse oscillations in a solar coronal loop

White

Verwichte

2021

A&A

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Context. Magnetohydrodynamic (MHD) waves play an important role in the dynamics and heating of the solar corona. Their investigation also reveals information about the local conditions. Transverse (Alfvénic) oscillations of loops commonly occur in response to solar eruptions. It has been shown that these oscillations elicit an acoustic response through wave coupling at the footpoint and the pondermotive force. Aims. We extend the modelling of wave coupling between a transverse loop oscillation and slow magnetoacoustic waves through line-tied footpoint boundary conditions by considering the effect of transverse loop structuring and nonlinearity. Methods. We combine analytical wave modelling with fully nonlinear MHD simulations to study the wave field of propagating slow waves in a two-dimensional slab loop (arcade) model. Results. We demonstrate that transverse loop oscillations generate propagating slow waves from both footpoint with the same periodicity but shorter wavelength determined by the local sound speed. The degree of wave coupling is proportional to the square root of the plasma-β. The slow wave field is anti-symmetric in the direction of transverse wave polarisation. We show through synthetic diagnostics that this has important consequences for their observability in terms of the orientation of the loop with respect to the observer. We also show that for the interpretation of intensity oscillations associated with typical loop oscillations the ponderomotive response also needs to be taken into account. The modelling presented here allows for the successful identification of the slow waves and pondermotive response in a previous observational study.

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Excitation and evolution of vertically polarised transverse loop oscillations by coronal rain

Cited by 24 publications

References 28 publications

Kink Oscillations of Coronal Loops

Kink Oscillations of Coronal Loops

Non-damping oscillations at flaring loops

Acoustic response to transverse oscillations in a solar coronal loop

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