An Introduction to Helioseismology

Christensen‐Dalsgaard, J.; Däppen, Werner; Dziembowski, W. A.; Guzik, Joyce A.

doi:10.1007/978-94-011-4299-1_2

Cited by 42 publications

(39 citation statements)

References 232 publications

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“…In the interior model, we used the OPAL opacities (Iglesias & Rogers 1996) that were extended to low temperatures with the opacities of Alexander & Ferguson (1994) and the CEFF equation of state (Christensen-Dalsgaard & Däppen 1992). The metallicity was assumed to be Z = 0.02 for the metal mixture derived by Grevesse & Noels (1993).…”

Section: Physical Inputmentioning

confidence: 99%

Solar-like oscillations in massive main-sequence stars

Belkacem¹,

Dupret²,

Noels³

2010

A&A

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Motivated by the detection of stochastically excited modes in the massive star V1449 Aql, which is already known to be a β Cephei star, we theoretically investigate the driving by turbulent convection. By using a full non-adiabatic computation of the damping rates, together with a computation of the energy injection rates, we provide an estimate of the amplitudes of modes excited by both the convective region induced by the iron opacity bump and the convective core. Despite the uncertainties in the dynamical properties of these convective regions, we demonstrate that both regions are able to efficiently excite p modes above the CoRoT observational threshold and the solar amplitudes. In addition, we emphasise the potential asteroseismic diagnostics provided by each convective region, which we hope will help us to identify the region responsible for solar-like oscillations, and to place constraints on this convective zone. A forthcoming work will be dedicated to an extended investigation of the likelihood of solar-like oscillations across the Hertzsprung-Russell diagram.

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Section: Physical Inputmentioning

confidence: 99%

Solar-like oscillations in massive main-sequence stars

Belkacem¹,

Dupret²,

Noels³

2010

A&A

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“…The equilibrium stellar models were computed with the evolutionary code CLÉS (Code Liégeois d'Évolution Stellaire) that uses: standard MLT for convection calculations; the OPAL opacities (Iglesias & Rogers 1996) completed at low temperatures with the opacities of Alexander & Ferguson (1994); the CEFF equation of state (Christensen-Dalsgaard & Däppen 1992); and the atmosphere models of Kurucz (1998) as boundary conditions. All the models of this study have a chemical composition given by: (X = 0.7, Z = 0.02) and a convective core overshooting parameter α ov = 0.2.…”

Section: Introductionmentioning

confidence: 99%

Convection-pulsation coupling

Dupret¹,

Grigahcène²,

Garrido³

et al. 2005

A&A

283

352

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Abstract. We apply here the Time Dependent Convection (TDC) treatment presented in our earlier paper in this series to the study of δ Sct and γ Dor pulsating stars. Stabilization of the δ Sct p-modes at the red edge of the Instability Strip (IS) and the driving of the γ Dor g-modes are explained by our models. Theoretical IS obtained with different values of the Mixing Length (ML) parameter α are compared to observations and a good agreement is obtained for α between 1.8 and 2. The influence of each term of our TDC treatment (perturbation of convective flux, turbulent pressure, and turbulent kinetic energy dissipation) on the eigenfrequencies and on the driving and damping mechanisms is investigated. Finally, we show that our TDC models predict the likely existence of hybrid stars with both δ Sct p-modes and γ Dor g-modes oscillations.

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“…Some of this discrepancy may be resolved by altering the diffusion-produced composition profile at the base of the convection zone, perhaps through changes in the diffusion coefficients, or mixing due to differential rotation or gravity modes (see, e.g., [6], [29]). Several studies have shown that much of the discrepancy below the convection zone can be removed by a prescribed change in the opacity profile of 1 to ~5% [26,27], well within the uncertainties in opacity calculations. Calculations have been done including the effects of radiative levitation of individual elements in addition to diffusive settling; these calculations show that radiative levitation effects are quite small, amounting to a change of only 0.5% in opacity due to the different resulting element distribution, and a change of 0.06% in sound speed below the convection zone [30].…”

Section: Comments On Other Sources Of Uncertaintiesmentioning

confidence: 96%

“…This diffusion is very slow, and impeded by the convective mixing in the envelope; however, during the Sun's 4.5 billion-year lifetime, about 10 percent of the initial helium and ~8 percent of the surface heavier elements can settle from the convection zone. This diffusion has a significant effect on the Sun's structure (see, e.g., [5], [6], [26]). …”

Section: Solar Evolution Modelingmentioning

confidence: 99%

Helioseismic Tests of Radiative Opacities

Guzik¹,

Neuforge-Verheecke²,

Keady³

et al. 2002

AIP Conference Proceedings

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Abstract. During the past fifteen years, thousands of solar acoustic oscillation modes have been measured to remarkable precision, in many cases to within 0.01%. These frequencies have been used to infer the interior structure of the sun and test the physical input to solar models. Here we summarize the procedures, input physics and assumptions for calculating a standard solar evolution model. We compare the observed and calculated sound speed profile and oscillation frequencies of solar models calibrated using the new Los Alamos LEDCOP [1] and Livermore OPAL [2] Rosseland mean opacities for the same element mixture. We show that solar oscillations are extremely sensitive to opacities, with opacity differences of only a few percent producing an easily detectable effect on the sound speed and predicted frequencies [3]. The oscillation data indicate that agreement would be improved by an opacity increase of several percent below the convection zone for both the LEDCOP and OPAL opacities.

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An Introduction to Helioseismology

Cited by 42 publications

References 232 publications

Solar-like oscillations in massive main-sequence stars

Solar-like oscillations in massive main-sequence stars

Convection-pulsation coupling

Helioseismic Tests of Radiative Opacities

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