Magnetohydrodynamic Oscillations in the Solar Corona and Earth’s Magnetosphere: Towards Consolidated Understanding

Often the enhanced electromagnetic radiation generated in solar and stellar flares shows a pronounced (quasi)-oscillatory pattern-quasi-periodic pulsations (QPP), with characteristic periods ranging from a fraction of a second to several tens of minutes. We review recent advances in the empirical study of QPP in solar and stellar flares, addressing the intrinsic nonstationarity of the signal, i.e. the variation of its amplitude, period or phase with time. This nonstationarity could form a basis for a classification of QPP, necessary for revealing specific physical mechanisms responsible for their appearance. We could identify two possible classes of QPP, decaying harmonic oscillations, and trains of symmetric triangular pulsations. Apparent similarities between QPP and irregular geomagnetic pulsations Pi offer a promising avenue for the knowledge transfer in both analytical techniques and theory. Attention is also paid to the effect of the flare trend on the detection and analysis of QPP.

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“…[13,30] for detailed reviews. In a nutshell, the method treats the signal of interest as a superposition of many active intrinsic time scales.…”

Section: Qpp Detection and Analysismentioning

confidence: 99%

“…Moreover, theoretical interpretations of geomagnetic irregular pulsations operate by the same models as used in the QPP study, namely the mechanisms based upon various resonances of MHD waves, and repetitive regimes of magnetic reconnection (see, e.g. [13]). …”

Section: Similarity Of Qpp In Flares and Geomagnetic Pi Pulsationsmentioning

confidence: 99%

Non-stationary quasi-periodic pulsations in solar and stellar flares

Nakariakov

Kolotkov

Kupriyanova

et al. 2018

Plasma Phys. Control. Fusion

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“…An important phenomenon is a coalescence of two magnetic islands, which occurs in the interaction of two twisted magnetic flux tubes (ropes) of the same sign of helicity. This process is believed to occur in very different plasma environments, for instance the solar corona [e.g., 3,4], the Earth's magnetosphere [e.g., 4,5], magnetar atmospheres [e.g., 6], and laboratory plasmas [e.g. , 7].…”

Section: Introductionmentioning

confidence: 99%

Nonlinear oscillations of coalescing magnetic flux ropes

2016

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An analytical model of highly nonlinear oscillations occurring during a coalescence of two magnetic flux ropes, based upon two-fluid hydrodynamics, is developed. The model accounts for the effect of electric charge separation, and describes perpendicular oscillations of the current sheet formed by the coalescence. The oscillation period is determined by the current sheet thickness, the plasma parameter β, and the oscillation amplitude. The oscillation periods are typically greater or about the ion plasma oscillation period. In the nonlinear regime, the oscillations of the ion and electron concentrations have a shape of a narrow symmetric spikes.PACS numbers: 52.35.

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“…Jess et al 2015;Nakariakov et al 2016, for recent comprehensive reviews). During the last few decades these waves have been intensively studied observationally, from ground and space based instruments, and theoretically, in particular as a possible source of coronal plasma heating and solar wind acceleration.…”

Section: Introductionmentioning

confidence: 99%

Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves

Nakariakov

Afanasyev

Kumar

et al. 2017

ApJ

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Evolution of slow magnetoacoustic waves guided by a cylindrical magnetic flux tube that represents a coronal loop or plume, is modelled accounting for the effects of finite gas pressure, weak nonlinearity, dissipation by thermal conduction and viscosity, and the misbalance between the cooling by optically thin radiation and unspecified heating of the plasma. An evolutionary equation of the Burgers-Malthus type is derived. It is shown that the cooling/heating misbalance, determined by the derivatives of the combined radiative cooling and heating function, with respect to the density, temperature and magnetic field at the thermal equilibrium affect the wave rather strongly. This effect may either cause additional damping, or counteract it, or lead to the gradual amplification of the wave. In the latter case the coronal plasma acts as an active medium for the slow magnetoacoustic waves. The effect of the cooling/heating misbalance could be important for coronal slow waves, and could be responsible for certain discrepancies between theoretical results and observations, in particular the increased or decreased damping lengths and times, detection of the waves at certain heights only, and excitation of compressive oscillations. The results obtained open up a possibility for the diagnostics of the coronal heating function by slow magnetoacoustic waves.

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Magnetohydrodynamic Oscillations in the Solar Corona and Earth’s Magnetosphere: Towards Consolidated Understanding

Cited by 179 publications

References 374 publications

Non-stationary quasi-periodic pulsations in solar and stellar flares

Non-stationary quasi-periodic pulsations in solar and stellar flares

Nonlinear oscillations of coalescing magnetic flux ropes

Effect of Local Thermal Equilibrium Misbalance on Long-wavelength Slow Magnetoacoustic Waves

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