Numerical Modeling of Magnetohydrodynamic Wave Propagation and Refraction in Sunspots

Khomenko, E.; Collados, M.

doi:10.1086/507760

Cited by 166 publications

(202 citation statements)

References 32 publications

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“…The numerical MHD code is described in detail in Khomenko & Collados (2006); . The unperturbed magnetostatic sunspot model is taken from .…”

Section: Description Of Methodsmentioning

confidence: 99%

Sunspot seismic halos generated by fast MHD wave refraction

Khomenko

Collados²

2009

A&A

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Aims. We suggest an explanation for the high-frequency power excess surrounding active regions known as seismic halos. Methods. We use numerical simulations of magneto-acoustic wave propagation in a magnetostatic sunspot model. Results. We propose that seismic halos can be caused by the additional energy injected by high-frequency fast mode waves refracted in the higher atmosphere due to the rapid increase of the Alfvén speed. Our model qualitatively explains the magnitude of the halo and allows us to make predictions of its behavior that can be checked in future observations.

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“…The numerical MHD code is described in detail in Khomenko & Collados (2006); . The unperturbed magnetostatic sunspot model is taken from .…”

Section: Description Of Methodsmentioning

confidence: 99%

Sunspot seismic halos generated by fast MHD wave refraction

Khomenko

Collados²

2009

A&A

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“…Recently, linear and nonlinear magneto-acoustic wave propagation through a magnetic flux tube has been studied numerically by Cargill et al (1997), Bogdan et al (2003), Hasan et al (2005), Carlsson & Bogdan (2006), Khomenko & Collados (2006), Khomenko et al (2008), Hasan & van Ballegooijen (2008), Taroyan & Erdélyi (2009), Ofman (2009, and others. The properties of wave propagation in such numerical simulations, as in the real Sun, are highly sensitive to the properties of the background atmosphere and Figure 1.…”

Section: Introductionmentioning

confidence: 99%

“…A non-uniform and non-potential magnetic field configuration embedded in a non-uniform photospheric model has been investigated by Khomenko & Collados (2006) to study the processes taking place around the equipartition layer (where V A = C S ) in sunspots.…”

Section: Introductionmentioning

confidence: 99%

Numerical Modeling of Footpoint-Driven Magneto-Acoustic Wave Propagation in a Localized Solar Flux Tube

Fedun

Shelyag

Erdélyi

2010

ApJ

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In this paper, we present and discuss results of two-dimensional simulations of linear and nonlinear magnetoacoustic wave propagation through an open magnetic flux tube embedded in the solar atmosphere expanding from the photosphere through to the transition region and into the low corona. Our aim is to model and analyze the response of such a magnetic structure to vertical and horizontal periodic motions originating in the photosphere. To carry out the simulations, we employed our MHD code SAC (Sheffield Advanced Code). A combination of the VALIIIC and McWhirter solar atmospheres and coronal density profiles were used as the background equilibrium model in the simulations. Vertical and horizontal harmonic sources, located at the footpoint region of the open magnetic flux tube, are incorporated in the calculations, to excite oscillations in the domain of interest. To perform the analysis we have constructed a series of time-distance diagrams of the vertical and perpendicular components of the velocity with respect to the magnetic field lines at each height of the computational domain. These time-distance diagrams are subject to spatio-temporal Fourier transforms allowing us to build ω-k dispersion diagrams for all of the simulated regions in the solar atmosphere. This approach makes it possible to compute the phase speeds of waves propagating throughout the various regions of the solar atmosphere model. We demonstrate the transformation of linear slow and fast magneto-acoustic wave modes into nonlinear ones, i.e., shock waves, and also show that magneto-acoustic waves with a range of frequencies efficiently leak through the transition region into the solar corona. It is found that the waves interact with the transition region and excite horizontally propagating surface waves along the transition region for both types of drivers. Finally, we estimate the phase speed of the oscillations in the solar corona and compare it with the phase speed derived from observations.

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“…A more complete understanding of the problem perhaps could be reached via direct forward modeling of helioseismological data, since magnetic fields of arbitrary configuration can be used. Several recent works report efforts in this direction, e.g., Gizon et al (2006), Khomenko & Collados (2006), Parchevsky & Kosovichev (2007), Shelyag et al (2007), Hanasoge (2008), andCameron et al (2008). In all these works (except Shelyag et al 2007), the authors apply a similar strategy.…”

Section: Introductionmentioning

confidence: 99%

Magnetohydrostatic Sunspot Models from Deep Subphotospheric to Chromospheric Layers

Khomenko

Collados

2008

Astrophysical Journal

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In order to understand the influence of magnetic fields on the propagation properties of waves, as derived from different local helioseismology techniques, forward modeling of waves is required. Such calculations need a model in magnetohydrostatic equilibrium as an initial atmosphere through which to propagate oscillations. We provide a method to construct such a model in equilibrium for a wide range of parameters, for use in simulations of artificial helioseismologic data. The method combines the advantages of self-similar solutions and current-distributed models. A set of models is developed by numerical integration of magnetohydrostatic equations from the subphotospheric to chromospheric layers.

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Numerical Modeling of Magnetohydrodynamic Wave Propagation and Refraction in Sunspots

Cited by 166 publications

References 32 publications

Sunspot seismic halos generated by fast MHD wave refraction

Sunspot seismic halos generated by fast MHD wave refraction

Numerical Modeling of Footpoint-Driven Magneto-Acoustic Wave Propagation in a Localized Solar Flux Tube

Magnetohydrostatic Sunspot Models from Deep Subphotospheric to Chromospheric Layers

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