Realistic Numerical Simulations of Solar Convection and Oscillations in Magnetic Regions

Jacoutot, L.; Kosovichev, A. G.; Wray, A. A.; Mansour, Nagi N.

doi:10.1086/592042

Cited by 62 publications

(71 citation statements)

References 26 publications

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“…The hypothesis of an altered wave excitation mechanism due to the presence of magnetic fields was proposed by Brown et al (1992) and Braun et al (1992) and revisited more recently by Jacoutot et al (2008). Of course, it is also equally likely that the substantial differences in the wave-propagation physics in active regions could also be leading to these enhancements, a possibility noted by a number of authors (e.g.…”

Section: Theoriesmentioning

confidence: 98%

Modeling the Subsurface Structure of Sunspots

et al. 2010

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While sunspots are easily observed at the solar surface, determining their subsurface structure is not trivial. There are two main hypotheses for the subsurface structure of sunspots: the monolithic model and the cluster model. Local helioseismology is the only means by which we can investigate subphotospheric structure. However, as current linear inversion techniques do not yet allow helioseismology to probe the internal structure with sufficient confidence to distinguish between the monolith and cluster models, the development of physically realistic sunspot models are a priority for helioseismologists. This is because they are not only important indicators of the variety of physical effects that may influence helioseismic inferences in active regions, but they also enable detailed assessments of the validity of helioseismic interpretations through numerical forward modeling. In this article, we provide a critical review of the existing sunspot models and an overview of numerical methods employed to model wave propagation through model sunspots. We then carry out a helioseismic analysis of the sunspot in Active Region 9787 and address the serious inconsistencies uncovered by Gizon et al. (2009aGizon et al. ( , 2009b. We find that this sunspot is most probably associated with a shallow, positive wave-speed perturbation (unlike the traditional two-layer model) and that travel-time measurements are consistent with a horizontal outflow in the surrounding moat.

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Section: Theoriesmentioning

confidence: 98%

Modeling the Subsurface Structure of Sunspots

et al. 2010

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“…Observed distributions: circles SoHo-GOLF, squares BISON, and triangles GONG for l = 1 [65]. b) Logarithm of the work integrand in units of erg cm −2 s −1 ), as a function of depth and frequency for numerical simulations with the dynamic turbulence model [66].…”

Section: Excitation By Turbulent Convectionmentioning

confidence: 99%

“…The peaks on the top of the smooth background spectrum of turbulent convection represent oscillation modes: the sharp asymmetric peaks below 6 mHz are resonant normal modes, while the broader peaks above 6 mHz, which become stronger in magnetic regions, correspond to pseudo-modes. [66] 3.5 Impulsive excitation: sunquakes "Sunquakes", the helioseismic response to solar flares, are caused by strong localized hydrodynamic impacts in the photosphere during the flare impulsive phase. The helioseismic waves have been observed directly as expanding circular-shaped ripples in SOHO/MDI Dopplergrams [90] (Fig.…”

Section: Magnetic Effects: Sunspot Oscillations and Acoustic Halosmentioning

confidence: 99%

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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“…It has been used for the investigation of oscillatory and dynamical properties of solar magnetoconvection (e.g. Jacoutot et al 2008a;Kitiashvili et al 2011a,b), and compared with high-resolution observations (e.g. Kitiashvili et al 2010Kitiashvili et al , 2013.…”

Section: Realistic Modeling Of Stellar Convectionmentioning

confidence: 99%

Radiative hydrodynamic simulations of turbulent convection and pulsations of Kepler target stars

Kitiashvili

2013

Proc. IAU

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Abstract. The problem of interaction of stellar pulsations with turbulence and radiation in stellar convective envelopes is central to our understanding of excitation mechanisms, oscillation amplitudes and frequency shifts. Realistic ("ab initio") numerical simulations provide unique insights into the complex physics of pulsation-turbulence-radiation interactions, as well as into the energy transport and dynamics of convection zones, beyond the standard evolutionary theory. 3D radiative hydrodynamics simulations have been performed for several Kepler target stars, from M-to A-class along the main sequence, using a new 'StellarBox' code, which takes into account all essential physics and includes subgrid scale turbulence modeling. The results reveal dramatic changes in the convection and pulsation properties among stars of different mass. For relatively massive stars with thin convective envelopes, the simulations allow us to investigate the dynamics the whole envelope convection zone including the overshoot region, and also look at the excitation of internal gravity waves. Physical properties of the turbulent convection and pulsations, and the oscillation spectrum for two of these targets are presented and discussed in this paper. In one of these stars, with mass 1.47 M , we simulate the whole convective zone and investigate the overshoot region at the boundary with the radiative zone.

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Realistic Numerical Simulations of Solar Convection and Oscillations in Magnetic Regions

Cited by 62 publications

References 26 publications

Modeling the Subsurface Structure of Sunspots

Modeling the Subsurface Structure of Sunspots

Advances in Global and Local Helioseismology: An Introductory Review

Radiative hydrodynamic simulations of turbulent convection and pulsations of Kepler target stars

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