Numerical simulations of magnetoacoustic oscillations in a gravitationally stratified solar corona

Konkol, P.; Murawski, K.; Zaqarashvili, T. V.

doi:10.1051/0004-6361/201117943

Cited by 16 publications

(13 citation statements)

References 24 publications

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“…The first vortex results from the initial pulse in Vy , which is a characteristic feature of velocity perturbations (Murawski et al 2013b). Such vortices were also theorized by Konkol, Murawski, Zaqarashvili (2012) in a similar but 2D context. The observed vertical vortices are located at the height below 1 Mm that possesses a very high plasma beta.…”

Section: Vertical Perturbationmentioning

confidence: 56%

Three-dimensional numerical simulation of magnetohydrodynamic-gravity waves and vortices in the solar atmosphere

Murawski

Ballai

Srivastava

et al. 2013

Monthly Notices of the Royal Astronomical Society

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With the adaptation of the FLASH code we simulate magnetohydrodynamic-gravity waves and vortices as well as their response in the magnetized three-dimensional (3D) solar atmosphere at different heights to understand the localized energy transport processes. In the solar atmosphere strongly structured by gravitational and magnetic forces, we launch a localized velocity pulse (in horizontal and vertical components) within a bottom layer of 3D solar atmosphere modeled by initial VAL-IIIC conditions, which triggers waves and vortices. The rotation direction of vortices depends on the orientation of an initial perturbation. The vertical driver generates magnetoacousticgravity waves which result in oscillations of the transition region, and it leads to the eddies with their symmetry axis oriented vertically. The horizontal pulse excites all magnetohydrodynamic-gravity waves and horizontally oriented eddies. These waves propagate upwards, penetrate the transition region, and enter the solar corona. In the high-beta plasma regions the magnetic field lines move with the plasma and the temporal evolution show that they swirl with eddies. We estimate the energy fluxes carried out by the waves in the magnetized solar atmosphere and conclude that such wave dynamics and vortices may be significant in transporting the energy to sufficiently balance the energy losses in the localized corona. Moreover, the structure of the transition region highly affects such energy transports, and causes the channeling of the propagating waves into the inner corona.

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Section: Vertical Perturbationmentioning

confidence: 56%

Three-dimensional numerical simulation of magnetohydrodynamic-gravity waves and vortices in the solar atmosphere

Murawski

Ballai

Srivastava

et al. 2013

Monthly Notices of the Royal Astronomical Society

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“…According to this model (see, e.g. Zhugzhda 2008;Botha et al 2011;Sych et al 2012), a broadband initial perturbation develops in a quasi-periodic wave train with the local acoustic cut-off frequency f ac ∝ cos θ/ √ T in the strong magnetic field of the umbra, where θ is the angle between the magnetic field and the vertical and T is the plasma temperature, see Bel & Leroy (1977) for the basic theory, and Konkol et al (2012) for example, and references therein for recent numerical simulations. Thus, assuming that the magnetic field lines in the sunspot atmosphere expand horizontally from the sunspot axis, the frequency f ac decreases in the horizontal direction with the distance from the sunspot axis.…”

Section: Discussionmentioning

confidence: 99%

Wave dynamics in a sunspot umbra

Сыч

Nakariakov

2014

A&A

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Context. Sunspot oscillations are one of the most frequently studied wave phenomena in the solar atmosphere. Understanding the basic physical processes responsible for sunspot oscillations requires detailed information about their fine structure. Aims. We aim to reveal the relationship between the fine horizontal and vertical structure, time evolution, and the fine spectral structure of oscillations in a sunspot umbra. Methods. The high spatial and time resolution data obtained with SDO/AIA for the sunspot in active region NOAA 11131 on 08 December 2010 were analysed with the time-distance plot technique and the pixelised wavelet filtering method. Different levels of the sunspot atmosphere were studied from the temperature minimum to the corona. Results. Oscillations in the 3 min band dominate in the umbra. The integrated spectrum of umbral oscillations contains distinct narrowband peaks at 1.9 min, 2.3 min, and 2.8 min. The power significantly varies in time, forming distinct 12-20 min oscillation trains. The oscillation power distribution over the sunspot in the horizontal plane reveals that the enhancements of the oscillation amplitude, or wave fronts, have a distinct structure consisting of an evolving two-armed spiral and a stationary circular patch at the spiral origin, situated near the umbra centre. This structure is seen from the temperature minimum at 1700 Å to the 1.6 MK corona at 193 Å. In time, the spiral rotates anti-clockwise. The wave front spirality is most pronounced during the maximum amplitude phases of the oscillations, and in the bandpasses where umbral oscillations have the highest power, 304 Å and 171 Å. In the low-amplitude phases the spiral breaks into arc-shaped patches. The 2D cross-correlation function shows that the oscillations at higher atmospheric levels occur later than at lower layers. The phase speed is estimated to be about 100 km s −1 . The fine spectral analysis shows that the central patch corresponds to the high-frequency oscillations, while the spiral arms highlight the lower-frequency oscillations in the 3 min band. Conclusions. The vertical and horizontal radial structure of the oscillations is consistent with the model that interprets umbral oscillations as slow magnetoacoustic waves filtered by the atmospheric temperature non-uniformity in the presence of the magnetic field inclination from the vertical. The mechanism for the polar-angle structure of the oscillations, in particular the spirality of the wave fronts, needs to be revealed.

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“…We additionally assume a current-free (∇ × B = 0) magnetic field whose horizontal B x , vertical B y , and transversal B z components are given as (Konkol et al 2012)…”

Section: Current-free Magnetic Field and The Hydrostaticmentioning

confidence: 99%

Two-fluid Numerical Simulations of Solar Spicules

Kuźma

Murawski

Kayshap

et al. 2017

ApJ

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We aim to study the formation and evolution of solar spicules by means of numerical simulations of the solar atmosphere. With the use of newly developed JOANNA code, we numerically solve two-fluid (for ions + electrons and neutrals) equations in 2D Cartesian geometry. We follow the evolution of a spicule triggered by the time-dependent signal in ion and neutral components of gas pressure launched in the upper chromosphere. We use the potential magnetic field, which evolves self-consistently, but mainly plays a passive role in the dynamics. Our numerical results reveal that the signal is steepened into a shock that propagates upward into the corona. The chromospheric cold and dense plasma lags behind this shock and rises into the corona with a mean speed of 20-25 km s −1 . The formed spicule exhibits the upflow/downfall of plasma during its total lifetime of around 3-4 minutes, and it follows the typical characteristics of a classical spicule, which is modeled by magnetohydrodynamics. The simulated spicule consists of a dense and cold core that is dominated by neutrals. The general dynamics of ion and neutral spicules are very similar to each other. Minor differences in those dynamics result in different widths of both spicules with increasing rarefaction of the ion spicule in time.

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Numerical simulations of magnetoacoustic oscillations in a gravitationally stratified solar corona

Cited by 16 publications

References 24 publications

Three-dimensional numerical simulation of magnetohydrodynamic-gravity waves and vortices in the solar atmosphere

Three-dimensional numerical simulation of magnetohydrodynamic-gravity waves and vortices in the solar atmosphere

Wave dynamics in a sunspot umbra

Two-fluid Numerical Simulations of Solar Spicules

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