Effect of Suppressed Excitation on the Amplitude Distribution of 5 Minute Oscillations in Sunspots

Parchevsky, K. V.; Kosovichev, A. G.

doi:10.1086/521602

Cited by 47 publications

(43 citation statements)

References 19 publications

(26 reference statements)

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“…The sources are impulsive, with a dominant frequency of 3.2 mHz. The use of impulsive sources placed at a constant shallow depth is consistent with observational constraints (e.g., Nigam & Kosovichev 1999) and has been validated in earlier studies (e.g., Tong et al 2003b;Shelyag et al 2006;Parchevsky & Kosovichev 2007;Parchevsky et al 2008;Cobden et al 2010). …”

Section: Generation Of Synthetic Datasupporting

confidence: 73%

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

Cobden¹,

Tong²,

Warner³

2011

ApJ

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We present the first results from the inversion of full acoustic wavefield in the helioseismic context. In contrast to time-distance helioseismology, which involves analyzing the travel times of seismic waves propagating into the solar interior, wavefield tomography models both the travel times and amplitude variations present in the entire seismic record. Unlike the use of ray-based, Fresnel-zone, Born, or Rytov approximations in previous time-distance studies, this method does not require any simplifications to be made to the sensitivity kernel in the inversion. In this study, the acoustic wavefield is simulated for all iterations in the inversion. The sensitivity kernel is therefore updated while lateral variations in sound-speed structure in the model emerge during the course of the inversion. Our results demonstrate that the amplitude-based inversion approach is capable of resolving sound-speed structures defined by relatively sharp vertical and horizontal boundaries. This study therefore provides the foundation for a new type of subsurface imaging in local helioseismology that is based on the inversion of the entire seismic wavefield.

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Section: Generation Of Synthetic Datasupporting

confidence: 73%

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

Cobden¹,

Tong²,

Warner³

2011

ApJ

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“…Threedimensional numerical simulations of this effect have shown that the reduction of acoustic emissivity can explain at least 50% of the observed power deficit in sunspots ( Fig. 8) [83]. Another significant contribution comes from the amplitude changes caused by variations in the background conditions.…”

Section: Magnetic Effects: Sunspot Oscillations and Acoustic Halosmentioning

confidence: 95%

Advances in Global and Local Helioseismology: An Introductory Review

Kosovichev

2011

The Pulsations of the Sun and the Stars

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Abstract. Helioseismology studies the structure and dynamics of the Sun's interior by observing oscillations on the surface. These studies provide information about the physical processes that control the evolution and magnetic activity of the Sun. In recent years, helioseismology has made substantial progress towards the understanding of the physics of solar oscillations and the physical processes inside the Sun, thanks to observational, theoretical and modeling efforts. In addition to the global seismology of the Sun based on measurements of global oscillation modes, a new field of local helioseismology, which studies oscillation travel times and local frequency shifts, has been developed. It is capable of providing 3D images of the subsurface structures and flows. The basic principles, recent advances and perspectives of global and local helioseismology are reviewed in this article.

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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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Effect of Suppressed Excitation on the Amplitude Distribution of 5 Minute Oscillations in Sunspots

Cited by 47 publications

References 19 publications

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

Inversion of Full Acoustic Wavefield in Local Helioseismology: A Study With Synthetic Data

Advances in Global and Local Helioseismology: An Introductory Review

Magnetohydrostatic Sunspot Models from Deep Subphotospheric to Chromospheric Layers

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