The CoRoT primary target HD 52265: models and seismic tests

Soriano, M. Flores; Vauclair, S.; Vauclair, G.; Laymand, M.

doi:10.1051/0004-6361:20066798

Cited by 22 publications

(35 citation statements)

References 27 publications

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“…According to Eqs. (6)-(8) that are presented as modified by Soriano et al (2007Soriano et al ( , 2008, we postulate that the most likely reason is that the central density increases with evolution. It can affect the modes of the lowest degrees most significantly, and particularly for modes of the lowest degrees that penetrate most deeply, and hence affect δν 0,2 more than δν 1,3 , leading to the dependence of r 01 on absolute age.…”

Section: The Ratio R 01mentioning

confidence: 87%

“…This contradicts the so-called "asymptotic theory" developed by Tassoul (1980). To solve this problem and understand how small separations can become negative, Soriano et al (2007) modified the approximate expression for ν n,l :…”

Section: The Ratio R 01mentioning

confidence: 99%

“…(5), both the large and small separations can be obtained. However, Soriano et al (2007) and Soriano & Vauclair (2008) found that the small separations in some cases became negative when they used the adiabatic code to compute the acoustic frequencies. This contradicts the so-called "asymptotic theory" developed by Tassoul (1980).…”

Section: The Ratio R 01mentioning

confidence: 99%

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A new asteroseismic diagram of solar-like stars

Tang¹,

Gai

2008

A&A

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Aims. We attempt to develop a new asteroseismic diagram and investigate its characteristics, based on the ratio "r 01 " of adjacent, average, small separations. Methods. The ratio r 01 is defined following the asymptotic formula of stellar p-modes. Using the low-degree, theoretical, numerical value of adiabatic frequencies of stellar model, we compute the ratio r 01 and construct an additional asteroseismic diagram. Results. The additional asteroseismic diagram, which is similar to the C-D diagram (i.e. the famous asteroseismic HR diagram, socalled Christensen-Dalsgaard diagram), represents a composite of the average, large separations Δν and the ratio r 01 of the adjacent, small separations. A distinct separation is identified between the effects of varying both mass and age. The diagram can therefore provide information that is complementary to that provided by a C-D diagram, which can be used to estimate directly both the stellar mass and evolutionary state. Interestingly, the age of star can be derived from the new asteroseismic diagram. Furthermore, we investigate the parameter r 01 , which can be a useful direct indicator of stellar age.

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Section: The Ratio R 01mentioning

confidence: 87%

Section: The Ratio R 01mentioning

confidence: 99%

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A new asteroseismic diagram of solar-like stars

Tang¹,

Gai

2008

A&A

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“…For stars at the end of the main sequence, or at the beginning of the sub-giant branch, the small separations d ll+2 computed between l = 0 and l = 2 modes may become negative. The reason is that the helium accumulates Article published by EDP Sciences in the convective core, which leads to a slightly steeper variation of the sound speed than in the case of convection alone (Vauclair 2007;Soriano et al 2007;Soriano & Vauclair 2008).…”

Section: Introductionmentioning

confidence: 99%

Asteroseismic study of helium and heavy element diffusion in solar-type stars

Gai¹,

Bi²,

Tang³

et al. 2009

A&A

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Aims. Element diffusion is a basic physical element transport mechanism which induces the redistribution of chemical elements. Using the asteroseismic method, we study the effects of helium and heavy element diffusion on the internal structure and stellar evolution of solar-type stars. We also provide asteroseismic parameters for a grid of models which would be useful for direct comparison with the Kepler mission observations. Methods. We construct a grid of solar-type stellar models with various masses (from 0.8 M to 1.2 M ) and metallicities (Z i = 0.03, 0.025, 0.02, 0.015, 0.01, 0.005) with and without helium and heavy element diffusion. We compute "second differences" and "small separations" of the solar-metallicity models (Z i = 0.02) to analyze the effects of diffusion on the convection zone, helium abundance and the evolutionary sequence of the star. In order to study the asteroseismic property of models with and without diffusion, we compute the p-mode oscillation frequencies of low-degree modes for a grid of models and construct the ( Δν 0 , d 02 ) asteroseismic diagram. Results. We find that the element diffusion could speed up the evolution of the star, especially in the main sequence. The results show that it could enlarge the convective core and change the base of the convection envelope. In addition, the helium and heavy element diffusion make the models evolve to lower large and small separations in the asteroseismic diagram. This effect is more efficient at lower metallicity.

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“…They are related to the regions of partial reflection of the waves inside the stars, which occur for rapid variations of the sound velocity. The modulations of the small separations are directly related to the structure of the stellar cores (Roxburgh & Vorontsov 1994;Roxburgh 2007;Soriano et al 2007;Soriano & Vauclair 2008), whereas those of the large separation give information on the stellar upper layers, like the regions of helium ionization, the bottom of the convective zones or the diffusion-induced helium gradient (Vauclair & Théado 2004;Castro & Vauclair 2006). …”

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confidence: 99%

Precise characterisation of exoplanet-host stars parameters

Vauclair¹

2010

Proc. IAU

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Abstract. Studying the internal structure of exoplanet-host stars compared to that of similar stars without detected planets is particularly important for the understanding of planetary formation. In this framework, asteroseismic studies represent an excellent tool for a better characterization of stars and for a precise determination of the stellar parameters like mass, radius, gravity, effective temperature. The detection of stellar oscillations is obtained with the same instruments as used for the discovery of exoplanets, both from the ground and from space, although the time scales are very different. Here I discuss some details about the characterization of exoplanethost stars from seismology and the importance of the helium and heavy element abundances in this respect.

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The CoRoT primary target HD 52265: models and seismic tests

Cited by 22 publications

References 27 publications

A new asteroseismic diagram of solar-like stars

A new asteroseismic diagram of solar-like stars

Asteroseismic study of helium and heavy element diffusion in solar-type stars

Precise characterisation of exoplanet-host stars parameters

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