A new asteroseismic diagram of solar-like stars

Tang, Yanke; Bi, Shaolan; Gai, Ning

doi:10.1051/0004-6361:200809364

Cited by 5 publications

(2 citation statements)

References 19 publications

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“…Christensen-Dalsgaard (1988) suggested that a plot of δν against ∆ν can be used to determine stellar ages. Modifications to this so-called 'JCD diagram' have been suggested by Mazumdar (2005) and Tang et al (2008). However, this method does not work for more evolved stars (White et al, in preparation).…”

Section: Agementioning

confidence: 99%

An in-Depth Study of Grid-Based Asteroseismic Analysis

Gai

Basu

Chaplin

et al. 2011

ApJ

177

218

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NASA's Kepler mission is providing basic asteroseismic data for hundreds of stars. One of the more common ways of determining stellar characteristics from these data is by so-called "grid based" modelling. We have made a detailed study of grid-based analysis techniques to study the errors (and error-correlations) involved. As had been reported earlier, we find that it is relatively easy to get very precise values of stellar radii using grid-based techniques. However, we find that there are small, but significant, biases that can result because of the grid of models used. The biases can be minimized if metallicity is known. Masses cannot be determined as precisely as the radii, and suffer from larger systematic effects. We also find that the errors in mass and radius are correlated. A positive consequence of this correlation is that log g can be determined both precisely and accurately with almost no systematic biases. Radii and log g can be determined with almost no model dependence to within 5% for realistic estimates of errors in asteroseismic and conventional observations. Errors in mass can be somewhat higher unless accurate metallicity estimates are available. Age estimates of individual stars are the most model dependent. The errors are larger too. However, we find that for star-clusters, it is possible to get a relatively precise age if one assumes that all stars in a given cluster have the same age.

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Section: Agementioning

confidence: 99%

An in-Depth Study of Grid-Based Asteroseismic Analysis

Gai

Basu

Chaplin

et al. 2011

ApJ

177

218

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“…The most traditional asteroseismic diagram, which was proposed by Christensen-Dalsgaard (1984, 1988, 1993, is a very useful technique combining useful features of the frequency spectrum of stars to extract information about physical processes, for example helium and heavy element diffusion, in the stellar interior, that affect the frequencies. This well-known asteroseismic diagram exploits the fact that the average large separation of radial modes Δν 0 reflects the gross properties of a star, like its mass and radius, and the average small separation d 02 is more sensitive to the innermost layers of the star, and therefore to its evolutionary state (Mazumdar 2005;Tang et al 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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