Asteroseismology of binary stars and a compilation of core overshoot and rotational frequency values of OB stars

Aerts, C.

doi:10.1051/eas/1364045

Cited by 17 publications

(15 citation statements)

References 36 publications

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“…And the other way around, the "Group2" stars would then be intrinsically rapid rotators whose outer layers got spun down due to the angular momentum extracted from them by the IGWs. However, this hypothesis still contradicts the asteroseismic findings by [2] who found no correlation between the surface nitrogen abundance and the rotational frequency/projected rotational velocity of the star based on the multivariate statistical analysis of a sample of 70 B-type stars. Nevertheless, the IGWs can still be (and probably are) largely involved in the transport of the chemical elements inside stars.…”

Section: Internal Gravity Wavescontrasting

confidence: 61%

“…As it has been shown by [2], an extra mixing needs to be introduced in the terms of the core overshoot into the evolutionary models to match them with the observed seismic properties of binary components. However, it is barely the case for the majority of single stars of similar mass, where about the standard value of the core overshoot α = 0.2 is preferred, probably because the mass of a star can be way more relaxed in the modelling compared to the case of binary systems.…”

Section: Mass Discrepancymentioning

confidence: 99%

“…Nevertheless, the IGWs can still be (and probably are) largely involved in the transport of the chemical elements inside stars. Thus, it would be worth looking for a way to quantify the effect of the IGWs in massive stars and to include the corresponding parameter into the multivariate analysis similar to that performed by [2]. Should any correlation between the parameter describing the effect of the IGWs and the surface nitrogen abundance be found, this would point to the fact that the effect of the IGWs cannot be ignored when addressing the problem of the surface nitrogen enrichment in high-mass stars but must be taken into account along with the rotationally induced mixing.…”

Section: Internal Gravity Wavesmentioning

confidence: 99%

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Dynamical Asteroseismology: towards improving the theories of stellar structure and (tidal) evolution

Tkachenko

2017

EPJ Web Conf.

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Abstract. The potential of the dynamical asteroseismology, the research area that builds upon the synergies between the asteroseismology and binary stars research fields, is discussed in this manuscript. We touch upon the following topics: i) the mass discrepancy observed in intermediate-to high-mass main-sequence and evolved binaries as well as in the low mass systems that are still in the pre-main sequence phase of their evolution; ii) the rotationally induced mixing in high-mass stars, in particular how the most recent theoretical predictions and spectroscopic findings compare to the results of asteroseismic investigations; iii) internal gravity waves and their potential role in the evolution of binary star systems and surface nitrogen enrichment in high-mass stars; iv) the tidal evolution theory, in particular how its predictions of spin-orbit synchronisation and orbital circularisation compare to the present-day high-quality observations; v) the tidally-induced pulsations and their role in the angular momentum transport within binary star systems; vi) the scaling relations between fundamental and seismic properties of stars across the entire HR-diagram.

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Section: Internal Gravity Wavescontrasting

confidence: 61%

Section: Mass Discrepancymentioning

confidence: 99%

Section: Internal Gravity Wavesmentioning

confidence: 99%

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Dynamical Asteroseismology: towards improving the theories of stellar structure and (tidal) evolution

Tkachenko

2017

EPJ Web Conf.

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“…The DLEB samples in these investigations have typically been small, not exceeding a dozen or so systems (often far fewer), and have generally been restricted to the main sequence. Asteroseismic studies of single stars have so far been performed over limited ranges in mass and evolutionary state, but do suggest changes in overshooting that are not inconsistent with results described below (see, e.g., Aerts 2013;Deheuvels et al 2016).…”

Section: Introductionmentioning

confidence: 61%

The Dependence of Convective Core Overshooting on Stellar Mass: A Semi-empirical Determination Using the Diffusive Approach with Two Different Element Mixtures

Claret

Torres

2017

ApJ

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Convective core overshooting has a strong influence on the evolution of stars of moderate and high mass. Studies of double-lined eclipsing binaries and stellar oscillations have renewed interest in the possible dependence of overshooting on stellar mass, which has been poorly constrained by observations so far. Here we have used a sample of 29 well-studied double-lined eclipsing binaries in key locations of the H-R diagram to establish the explicit dependence of f ov on mass, where f ov is the free parameter in the diffusive approximation to overshooting. Measurements of the masses, radii, and temperatures of the binary components were compared against stellar evolution calculations based on the MESA code to infer semi-empirical values of f ov for each component. We find a clear mass dependence such that f ov rises sharply from zero in the range 1.2-2.0 M ⊙ , and levels off thereafter up to the 4.4 M ⊙ limit of our sample. Tests with two different element mixtures indicate the trend is the same, and we find it is also qualitatively similar to the one established in our previous study with the classical step-function implementation of overshooting characterized by the free parameter α ov . Based on these measurements we infer an approximate relationship between the two overshooting parameters of α ov /f ov = 11.36 ± 0.22, with a possible dependence on stellar properties.

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“…These authors reported hints that α ov may depend on mass even over this narrow range. Similar seismic studies of more massive stars (M > 7 M ; Aerts 2013Aerts , 2015 reported no obvious mass dependence.…”

Section: Introductionmentioning

confidence: 63%

The dependence of convective core overshooting on stellar mass

Claret

Torres

2016

A&A

110

118

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Context. Convective core overshooting extends the main-sequence lifetime of a star. Evolutionary tracks computed with overshooting are very different from those that use the classical Schwarzschild criterion, which leads to rather different predictions for the stellar properties. Attempts over the last two decades to calibrate the degree of overshooting with stellar mass using detached double-lined eclipsing binaries have been largely inconclusive, mainly because of a lack of suitable observational data. Aims. We revisit the question of a possible mass dependence of overshooting with a more complete sample of binaries, and examine any additional relation there might be with evolutionary state or metal abundance Z. Methods. We used a carefully selected sample of 33 double-lined eclipsing binaries strategically positioned in the H-R diagram with accurate absolute dimensions and component masses ranging from 1.2 to 4.4 M . We compared their measured properties with stellar evolution calculations to infer semi-empirical values of the overshooting parameter α ov for each star. Our models use the common prescription for the overshoot distance d ov = α ov H p , where H p is the pressure scale height at the edge of the convective core as given by the Schwarzschild criterion, and α ov is a free parameter. Results. We find a relation between α ov and mass, which is defined much more clearly than in previous work, and indicates a significant rise up to about 2 M followed by little or no change beyond this mass. No appreciable dependence is seen with evolutionary state at a given mass, or with metallicity at a given mass although the stars in our sample span a range of a factor of ten in [Fe/H], from −1.01 to +0.01.

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Asteroseismology of binary stars and a compilation of core overshoot and rotational frequency values of OB stars

Cited by 17 publications

References 36 publications

Dynamical Asteroseismology: towards improving the theories of stellar structure and (tidal) evolution

Dynamical Asteroseismology: towards improving the theories of stellar structure and (tidal) evolution

The Dependence of Convective Core Overshooting on Stellar Mass: A Semi-empirical Determination Using the Diffusive Approach with Two Different Element Mixtures

The dependence of convective core overshooting on stellar mass

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