MHD Wave Modes Resolved in Fine‐Scale Chromospheric Magnetic Structures

Verth, G.; Jess, D. B.

doi:10.1002/9781119055006.ch25

Cited by 27 publications

(13 citation statements)

References 99 publications

(170 reference statements)

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“…It is also unclear how to explain the observed periodicity if it is produced by Alfvén waves, as there have not been detections of coronal or chromospheric Alfvén waves with the detected periodicity (see e.g. Jess et al 2015;Verth & Jess 2016).…”

Section: Physical Mechanismmentioning

confidence: 99%

Origin of the Modulation of the Radio Emission from the Solar Corona by a Fast Magnetoacoustic Wave

Kolotkov

Nakariakov

Kontar

2018

ApJ

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Observational detection of quasi-periodic drifting fine structures in a type III radio burst associated with a solar flare SOL2015-04-16T11:22, with Low Frequency Array, is presented. Although similar modulations of the type III emission have been observed before and were associated with the plasma density fluctuations, the origin of those fluctuations was unknown. Analysis of the striae of the intensity variation in the dynamic spectrum allowed us to reveal two quasi-oscillatory components. The shorter component has the apparent wavelength of ∼ 2 Mm, phase speed of ∼ 657 km s −1 , which gives the oscillation period of ∼ 3 s, and the relative amplitude of ∼ 0.35%. The longer component has the wavelength of ∼ 12 Mm, and relative amplitude of ∼ 5.1%. The short frequency range of the detection does not allow us to estimate its phase speed. However, the properties of the shorter oscillatory component allowed us to interpret it as a fast magnetoacoustic wave guided by a plasma non-uniformity along the magnetic field outwards from the Sun. The assumption that the intensity of the radio emission is proportional to the amount of plasma in the emitting volume allowed us to show that the superposition of the plasma density modulation by a fast wave and a longer-wavelength oscillation of an unspecified nature could readily reproduce the fine structure of the observed dynamic spectrum. The observed parameters of the fast wave give the absolute value of the magnetic field in the emitting plasma of ∼ 1.1 G which is consistent with the radial magnetic field model.

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Section: Physical Mechanismmentioning

confidence: 99%

Origin of the Modulation of the Radio Emission from the Solar Corona by a Fast Magnetoacoustic Wave

Kolotkov

Nakariakov

Kontar

2018

ApJ

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“…Notably, compressible and incompressible MHD-wave modes can be excited in magnetic flux tubes, which act as waveguides, by reoccurring perturbations at their footpoints at photospheric heights [7]. Signatures of both standing and propagating incompressible (transverse) kink waves, as oscillatory pattern of velocities perpendicular to the assumed waveguides, have been observed in various structures in the solar photosphere and chromosphere such as small-scale bright points, spicules, fibrils, and mottles (e.g., [8][9][10][11][12][13][14][15][16]).…”

Section: Introductionmentioning

confidence: 99%

High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

Gómez

Jafarzadeh

Wedemeyer

et al. 2020

Phil. Trans. R. Soc. A.

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We report detection of oscillations in brightness temperature, size and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with high temporal resolution (i.e. 2 s cadence) with the Atacama large millimetre/ submillimetre array (ALMA) in Band 3 (centred at 3 mm; 100 GHz), exhibit three small-scale features with oscillatory behaviour with different, but overlapping, distributions of period on the order of, on average, 90 ± 22 s, 110 ± 12 s and 66 ± 23 s, respectively. We find anti-correlations between perturbations in brightness, temperature and size of the three features, which suggest the presence of fast sausage-mode waves in these small structures. In addition, the detection of transverse oscillations (although with a larger uncertainty) may also suggest the presence of Alfvénic oscillations which are likely representative of kink waves. This work demonstrates the diagnostic potential of high-cadence observations with ALMA for detecting high-frequency magnetohydrodynamic waves in the solar chromosphere. Such waves can potentially channel a vast amount of energy into the outer atmosphere of the Sun. This article is part of the Theo Murphy meeting issue ‘High-resolution wave dynamics in the lower solar atmosphere’.

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“…(2009) measured the amplitude of H α non‐thermal line broadening to be ∼0.05 Å (or a velocity amplitude on the order of 2.5 km s −1 ; upper‐right panel of Figure 4), and when combined with a plasma density of ∼10 −9 g cm −3 and a local Alfvén speed of ∼22 km s −1 , provided a wave energy flux equal to ∼150,000 W m −2 . While this quantity of energy is far in excess of the amount required to balance chromospheric radiative losses (Withbroe & Noyes, 1977), Verth and Jess (2016) hypothesized that the filling factor of such waves needs to be evaluated before the true importance of their existence can be evaluated. With this in mind, Fedun, Verth, et al.…”

Section: Waves In Structured Flux Tubes In the Chromospherementioning

confidence: 99%

Chromospheric Heating by Magnetohydrodynamic Waves and Instabilities

et al. 2021

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The importance of the chromosphere in the mass and energy transport within the solar atmosphere is now widely recognised. This review discusses the physics of magnetohydrodynamic (MHD) waves and instabilities in large-scale chromospheric structures as well as in magnetic flux tubes. We highlight a number of key observational aspects that have helped our understanding of the role of the solar chromosphere in various dynamic processes and wave phenomena, and the heating scenario of the solar chromosphere is also discussed. The review focuses on the physics of waves and invokes the basics of plasma instabilities in the context of this important layer of the solar atmosphere. Potential implications, future trends and outstanding questions are also delineated.

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MHD Wave Modes Resolved in Fine‐Scale Chromospheric Magnetic Structures

Cited by 27 publications

References 99 publications

Origin of the Modulation of the Radio Emission from the Solar Corona by a Fast Magnetoacoustic Wave

Origin of the Modulation of the Radio Emission from the Solar Corona by a Fast Magnetoacoustic Wave

High-frequency oscillations in small chromospheric bright features observed with Atacama Large Millimetre/Submillimetre Array

Chromospheric Heating by Magnetohydrodynamic Waves and Instabilities

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