Absolute dimensions of eclipsing binaries

Clausen, J. V.; Olsen, E. H.; Helt, B. E.; Claret, A.

doi:10.1051/0004-6361/200913700

Cited by 14 publications

(9 citation statements)

References 57 publications

(42 reference statements)

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“…When compared with the log Z/Z U V = −0.28 tracks (most similar to the best-fit metallicity of −0.31), however, both components fall along the corresponding mass track within the uncertainties. While this slightly higher metallicity appears to bring our observations in line with the models, we note that Clausen et al (2010) similarly found the components of V1130 Tau (1.31M and 1.39M , 1.49R and 1.78R , 6650 K and 6625 K, P = 0.8 d) approximately 200 K cooler then the corresponding Y 2 models (see their Figure 6) at their observed metallicity of log Z = −0.24 which may indicate a discrepancy with theory, although (like us) their abundances have not been derived in detail.…”

Section: Comparison With Evolutionary Modelssupporting

confidence: 74%

Fundamental Parameters of Kepler Eclipsing Binaries. I. Kic 5738698

Matson

Gies

Guo

et al. 2016

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Eclipsing binaries serve as a valuable source of stellar masses and radii that inform stellar evolutionary models and provide insight into additional astrophysical processes. The exquisite light curves generated by space-based missions such as Kepler offer the most stringent tests to date. We use the Kepler light curve of the 4.8 day eclipsing binary KIC 5739896 with ground based optical spectra to derive fundamental parameters for the system. We reconstruct the component spectra to determine the individual atmospheric parameters, and model the Kepler photometry with the binary synthesis code ELC to obtain accurate masses and radii. The two components of KIC 5738698 are F-type stars with M 1 = 1.39 ± 0.04M , M 2 = 1.34 ± 0.06M , and R 1 = 1.84 ± 0.03R , R 2 = 1.72 ± 0.03R . We also report a small eccentricity (e 0.0017) and unusual albedo values that are required to match the detailed shape of the Kepler light curve. Comparison with evolutionary models indicate an approximate age of 2.3 Gyr for the system.

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Section: Comparison With Evolutionary Modelssupporting

confidence: 74%

Fundamental Parameters of Kepler Eclipsing Binaries. I. Kic 5738698

Matson

Gies

Guo

et al. 2016

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“…Finally, we note that the ‘helium problem’ may not be limited to K dwarfs: systematic temperature offsets from the theoretical MS at low Z have been highlighted for FG dwarfs in the Geneva–Copenhagen survey (Nordström et al 2004); and a helium content Y = 0.23–0.24 (i.e. slightly subcosmological) has been recently suggested for a slightly metal‐poor F dwarf binary ([Fe/H]=−0.25; Clausen et al 2010). If the problem indeed extends to FG dwarfs, clearly some of the suggested solutions (for instance, those related to diffusion) are not viable.…”

Section: Summary and Discussionmentioning

confidence: 82%

Revisiting ΔY/ΔZ from multiple main sequences in globular clusters: insight from nearby stars

Portinari

Casagrande

Flynn

2010

Monthly Notices of the Royal Astronomical Society

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For nearby K dwarfs, the broadening of the observed main sequence (MS) at low metallicities is much narrower than expected from isochrones with the standard helium-to-metal enrichment ratio Y/ Z ∼ 2. Though the latter value fits well the MS around solar metallicity, and agrees with independent measurements from H II regions as well as with theoretical stellar yields and chemical evolution models, a much higher Y/ Z ∼ 10 is necessary to reproduce the broadening observed for nearby subdwarfs. This result resembles, on a milder scale, the very high Y/ Z estimated from the multiple MSs in ω Cen and NGC 2808. Although not 'inverted' as in ω Cen, where the metal-rich MS is bluer than the metal-poor one, the broadening observed for nearby subdwarfs is much narrower than stellar models predict for a standard helium content. We use this empirical evidence to argue that a revision of lower MS stellar models, suggested from nearby stars, could significantly reduce the helium content inferred for the subpopulations of those globular clusters. A simple formula based on empirically calibrated homology relations is constructed for an alternative estimate of Y/ Z in multiple MSs. We find that, under the most favourable assumptions, the estimated helium content for the enriched populations could decrease from Y 0.4 to as low as Y 0.3.

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“…VZ Hya, CTB08; V1130 Tau, Clausen et al 2010). It is, however, still too early to drawn any firm conclusions.…”

Section: Discussionmentioning

confidence: 99%

Absolute dimensions of solar-type eclipsing binaries

Clausen¹,

Bruntt

Olsen³

et al. 2010

A&A

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Context. Recent studies of inactive and active solar-type binaries suggest that chromospheric activity, and its effect on envelope convection, is likely to cause significant radius and temperature discrepancies. Accurate mass, radius, and abundance determinations from additional solar-type binaries exhibiting various levels of activity are needed for a better insight into the structure and evolution of these stars. Aims. We aim to determine absolute dimensions and abundances for the G0 V detached eclipsing binary EW Ori, and to perform a detailed comparison with results from recent stellar evolutionary models. Methods. uvby light curves and uvbyβ standard photometry were obtained with the Strömgren Automatic Telescope, published radial velocity observations from the CORAVEL spectrometer were reanalysed, and high-resolution spectra were observed at the FEROS spectrograph; all are/were ESO, La Silla facilities. State-of-the-art methods were applied for the photometric and spectroscopic analyses.Results. Masses and radii that are precise to 0.9% and 0.5%, respectively, have been established for both components of EW Ori. The 1.12 M secondary component reveals weak Ca ii H and K emission and is probably mildly active; no signs of activity are seen for the 1.17 M primary. We derive an [Fe/H] abundance of +0.05 ± 0.09 and similar abundances for Si, Ca, Sc, Ti, Cr, and Ni. Yonsai-Yale and Granada solar-scaled evolutionary models for the observed metal abundance reproduce the components fairly well at an age of ≈2 Gyr. Perfect agreement is, however, obtained at an age of 2.3 Gyr for a combination of a) a slight downwards adjustment of the envelope mixing length parameter for the secondary, as seen for other active solar-type stars; and b) a slightly lower helium content than prescribed by the Y − Z relations adopted for the standard model grids. The orbit is eccentric (e = 0.0758 ± 0.0020), and apsidal motion with a 62% relativistic contribution has been detected. The apsidal motion period is U = 16 300 ± 3900 yr, and the inferred mean central density concentration coefficient, log(k 2 ) = −1.66 ± 0.30, agrees marginally with model predictions. The measured rotational velocities, 9.0 ± 0.7 (primary) and 8.8 ± 0.6 (secondary) km s −1 , are in agreement with both the synchronous velocities and the theoretically predicted pseudo-synchronous velocities. Finally, the distance (175 ± 7 pc), age, and center-of mass velocity (6 km s −1 ) exclude suggested membership of the open cluster Collinder 70. Conclusions. EW Ori now belongs to the small group of solar-type eclipsing binaries with well-established astrophysical properties.

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Absolute dimensions of eclipsing binaries

Cited by 14 publications

References 57 publications

Fundamental Parameters of Kepler Eclipsing Binaries. I. Kic 5738698

Fundamental Parameters of Kepler Eclipsing Binaries. I. Kic 5738698

Revisiting ΔY/ΔZ from multiple main sequences in globular clusters: insight from nearby stars

Absolute dimensions of solar-type eclipsing binaries

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