Properties of the Hyades, the eclipsing binary HD 27130, and the oscillating red giant ϵ Tauri

Context. The derivation of accurate and precise masses and radii is possible for eclipsing binary stars, allowing for insights into their evolution. When residing in star clusters, they provide measurements of even greater precision, along with additional information on their properties. Asteroseismic investigations of solar-like oscillations offers similar possibilities for single stars. Aims. We wish to improve the previously established properties of the Hyades eclipsing binary HD 27130 and re-assess the asteroseismic properties of the giant star ϵ Tau. The physical properties of these members of the Hyades can be used to constrain the helium content and age of the cluster. Methods. New multi-colour light curves were combined with multi-epoch radial velocities to yield masses and radii of HD 27130. Measurements of Teff were derived from spectroscopy and photometry, and verified using the Gaia parallax. We estimated the cluster age from re-evaluated asteroseismic properties of ϵ Tau while using HD 27130 to constrain the helium content. Results. The masses, radii, and Teff of HD 27130 were found to be M = 1.0245 ± 0.0024 M⊙, R = 0.9226 ± 0.015 R⊙, Teff = 5650 ± 50 K for the primary, and M = 0.7426 ± 0.0016 M⊙, R = 0.7388 ± 0.026 R⊙, Teff = 4300 ± 100 K for the secondary component. Our re-evaluation of ϵ Tau suggests that the previous literature estimates are trustworthy and that the HIPPARCOS parallax is more reliable than the Gaia DR2 parallax. Conclusions. The helium content of HD 27130 and, thus, of the Hyades is found to be Y = 0.27 but with a significant model dependency. Correlations with the adopted metallicity result in a robust helium enrichment law, with ΔY/ΔZ close to 1.2 We estimate the age of the Hyades to be 0.9 ± 0.1 (stat) ±0.1 (sys) Gyr, which is in slight tension with recent age estimates based on the cluster white dwarfs. The precision of the age estimate can be much improved via asteroseismic investigations of the other Hyades giants and by future improvements to the Gaia parallax for bright stars.

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The TESS light curve of AI Phoenicis

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1662 ◽

2020 ◽

Vol 498 (1) ◽

pp. 332-343 ◽

Cited By ~ 5

Author(s):

P F L Maxted ◽

Patrick Gaulme ◽

D Graczyk ◽

K G Hełminiak ◽

C Johnston ◽

...

Keyword(s):

Light Curve ◽

Binary Stars ◽

Model Parameters ◽

Multiple Sources ◽

Light Curve Analysis ◽

Eclipsing Binary ◽

Eclipsing Binary Stars ◽

Free Parameters ◽

The Masses ◽

Stellar Masses

ABSTRACT Accurate masses and radii for normal stars derived from observations of detached eclipsing binary stars are of fundamental importance for testing stellar models and may be useful for calibrating free parameters in these model if the masses and radii are sufficiently precise and accurate. We aim to measure precise masses and radii for the stars in the bright eclipsing binary AI Phe, and to quantify the level of systematic error in these estimates. We use several different methods to model the Transiting Exoplanet Survey Satellite (TESS) light curve of AI Phe combined with spectroscopic orbits from multiple sources to estimate precisely the stellar masses and radii together with robust error estimates. We find that the agreement between different methods for the light-curve analysis is very good but some methods underestimate the errors on the model parameters. The semi-amplitudes of the spectroscopic orbits derived from spectra obtained with modern échelle spectrographs are consistent to within 0.1 per cent. The masses of the stars in AI Phe are $M_1 = 1.1938 \pm 0.0008\, \rm M_{\odot }$ and $M_2 = 1.2438 \pm 0.0008\, \rm M_{\odot }$, and the radii are $R_1 = 1.8050 \pm 0.0022\, \rm R_{\odot }$ and $R_2 = 2.9332 \pm 0.0023\, \rm R_{\odot }$. We conclude that it is possible to measure accurate masses and radii for stars in bright eclipsing binary stars to a precision of 0.2 per cent or better using photometry from TESS and spectroscopy obtained with modern échelle spectrographs. We provide recommendations for publishing masses and radii of eclipsing binary stars at this level of precision.

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Absolute properties of RU Cnc revisited: an active RS CVn-type eclipsing binary with red giant branch and main-sequence components

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2051 ◽

2019 ◽

Vol 488 (4) ◽

pp. 4520-4525 ◽

Cited By ~ 1

Author(s):

K A Çokluk ◽

D Koçak ◽

T İçli ◽

S Karaköse ◽

S Üstündağ ◽

...

Keyword(s):

Main Sequence ◽

Variation Analysis ◽

High Quality ◽

Eclipsing Binary ◽

Data Release ◽

Sequence Components ◽

Red Giant ◽

Period Decrease ◽

The Masses

ABSTRACT We present observations and analysis of an RS CVn-type double-lined eclipsing binary system, RU Cnc. The system has been observed for over a century. High-quality long-cadence observations, newly obtained from the Kepler K2 C5 and C18 campaigns, and two radial velocity curves were combined and analysed simultaneously, assuming a multispot model. The masses, radii and luminosities of the component stars have been precisely obtained as $M_\textrm{c} = 1.386\pm 0.044\, \mathrm{M}_{\odot }$, $M_\textrm{h} = 1.437 \pm 0.046\, \mathrm{M}_{\odot }$, $R_\textrm{h} = 2.39\pm 0.07\, \mathrm{R}_{\odot }$, $R_\textrm{c} = 5.02 \pm 0.08\, \mathrm{R}_{\odot }$, $L_\textrm{h} = 11.4\pm 1.2\, \mathrm{L}_{\odot }$ and$L_\textrm{c} = 12.0 \pm 1.0\, \mathrm{L}_{\odot }$, with a separation of $a = 27.914 \pm 0.016\, \mathrm{R}_{\odot }$. The distance of the system is determined to be $380\pm 57\,$ pc, which is consistent with the Gaia Data Release 2 result. Long-term detailed period variation analysis of the system indicates a period decrease of 7.9 × 10−7 d yr–1. The results suggest that the cooler component is on the red giant branch (RGB) and the hotter component is still on the main sequence.

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Multi-periodic pulsations of a stripped red-giant star in an eclipsing binary system

Nature ◽

10.1038/nature12192 ◽

2013 ◽

Vol 498 (7455) ◽

pp. 463-465 ◽

Cited By ~ 61

Author(s):

Pierre F. L. Maxted ◽

Aldo M. Serenelli ◽

Andrea Miglio ◽

Thomas R. Marsh ◽

Ulrich Heber ◽

...

Keyword(s):

Binary System ◽

Giant Star ◽

Eclipsing Binary ◽

Red Giant

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Absolute dimensions of the low-mass eclipsing binary system NSVS 10653195

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935516 ◽

2019 ◽

Vol 627 ◽

pp. A153 ◽

Cited By ~ 2

Author(s):

Ramón Iglesias-Marzoa ◽

María J. Arévalo ◽

Mercedes López-Morales ◽

Guillermo Torres ◽

Carlos Lázaro ◽

...

Keyword(s):

Binary Stars ◽

Binary Systems ◽

Eclipsing Binaries ◽

Low Mass Stars ◽

Orbital Inclination ◽

Eclipsing Binary ◽

Solar Metallicity ◽

Low Mass ◽

Stellar Models ◽

The Masses

Context. Low-mass stars in eclipsing binary systems show radii larger and effective temperatures lower than theoretical stellar models predict for isolated stars with the same masses. Eclipsing binaries with low-mass components are hard to find due to their low luminosity. As a consequence, the analysis of the known low-mass eclipsing systems is key to understand this behavior. Aims. We aim to investigate the mass–radius relation for low-mass stars and the cause of the deviation of the observed radii in low-mass detached eclipsing binary stars (LMDEB) from theoretical stellar models. Methods. We developed a physical model of the LMDEB system NSVS 10653195 to accurately measure the masses and radii of the components. We obtained several high-resolution spectra in order to fit a spectroscopic orbit. Standardized absolute photometry was obtained to measure reliable color indices and to measure the mean Teff of the system in out-of-eclipse phases. We observed and analyzed optical VRI and infrared JK band differential light-curves which were fitted using PHOEBE. A Markov chain Monte-Carlo (MCMC) simulation near the solution found provides robust uncertainties for the fitted parameters. Results. NSVS 10653195 is a detached eclipsing binary composed of two similar stars with masses of M1 = 0.6402 ± 0.0052 M⊙ and M2 = 0.6511 ± 0.0052 M⊙ and radii of R1 = 0.687+0.017−0.024 R⊙ and R2 = 0.672+0.018−0.022 R⊙. Spectral types were estimated to be K6V and K7V. These stars rotate in a circular orbit with an orbital inclination of i = 86.22 ± 0.61 degrees and a period of P = 0.5607222(2) d. The distance to the system is estimated to be d = 135.2+7.6−7.9 pc, in excellent agreement with the value from Gaia. If solar metallicity were assumed, the age of the system would be older than log (age) ∼ 8 based on the Mbol–log Teff diagram. Conclusions. NSVS 10653195 is composed of two oversized and active K stars. While their radii is above model predictions their Teff are in better agreement with models.

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Significant uncertainties from calibrating overshooting with eclipsing binary systems

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833568 ◽

2018 ◽

Vol 618 ◽

pp. A177 ◽

Cited By ~ 10

Author(s):

Thomas Constantino ◽

Isabelle Baraffe

Keyword(s):

Stellar Evolution ◽

Binary Stars ◽

Binary Systems ◽

Precise Measurement ◽

Main Sequence ◽

Stellar Mass ◽

Main Sequence Stars ◽

Eclipsing Binary ◽

The Masses ◽

Convective Boundaries

The precise measurement of the masses and radii of stars in eclipsing binary systems provides a window into uncertain processes in stellar evolution, especially mixing at convective boundaries. Recently, these data have been used to calibrate models of convective overshooting in the cores of main sequence stars. In this study we have used a small representative sample of eclipsing binary stars with 1.25 ≤ M/M⊙ < 4.2 to test how precisely this method can constrain the overshooting and whether the data support a universal stellar mass–overshooting relation. We do not recover the previously reported stellar mass dependence for the extent of overshooting and in each case we find there is a substantial amount of uncertainty, that is, the same binary pair can be matched by models with different amounts of overshooting. Models with a moderate overshooting parameter 0.013 ≤ fos ≤ 0.014 (using the scheme from Herwig et al. 1997, A&A, 324, L81) are consistent with all eight systems studied. Generally, a much larger range of f is suitable for individual systems. In the case of main sequence and early post-main sequence stars, large changes in the amount of overshooting have little effect on the radius and effective temperature, and therefore the method is of extremely limited utility.

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Asteroseismology of luminous red giants with Kepler. II. Dependence of mass loss on pulsations and radiation

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3970 ◽

2020 ◽

Author(s):

Jie Yu ◽

Saskia Hekker ◽

Timothy R Bedding ◽

Dennis Stello ◽

Daniel Huber ◽

...

Keyword(s):

Mass Loss ◽

Mass Loss Rate ◽

Asymptotic Giant Branch ◽

Red Giants ◽

Asymptotic Giant Branch Stars ◽

Chemical Enrichment ◽

Dust Mass ◽

Red Giant ◽

The Masses ◽

Loss Rates

Abstract Mass loss by red giants is an important process to understand the final stages of stellar evolution and the chemical enrichment of the interstellar medium. Mass-loss rates are thought to be controlled by pulsation-enhanced dust-driven outflows. Here we investigate the relationships between mass loss, pulsations, and radiation, using 3213 luminous Kepler red giants and 135000 ASAS–SN semiregulars and Miras. Mass-loss rates are traced by infrared colours using 2MASS and WISE and by observed-to-model WISE fluxes, and are also estimated using dust mass-loss rates from literature assuming a typical gas-to-dust mass ratio of 400. To specify the pulsations, we extract the period and height of the highest peak in the power spectrum of oscillation. Absolute magnitudes are obtained from the 2MASS Ks band and the Gaia DR2 parallaxes. Our results follow. (i) Substantial mass loss sets in at pulsation periods above ∼60 and ∼100 days, corresponding to Asymptotic-Giant-Branch stars at the base of the period-luminosity sequences C′ and C. (ii) The mass-loss rate starts to rapidly increase in semiregulars for which the luminosity is just above the red-giant-branch tip and gradually plateaus to a level similar to that of Miras. (iii) The mass-loss rates in Miras do not depend on luminosity, consistent with pulsation-enhanced dust-driven winds. (iv) The accumulated mass loss on the Red Giant Branch consistent with asteroseismic predictions reduces the masses of red-clump stars by 6.3%, less than the typical uncertainty on their asteroseismic masses. Thus mass loss is currently not a limitation of stellar age estimates for galactic archaeology studies.

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Testing convection in stellar models using detached eclipsing binaries

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307000336 ◽

2006 ◽

Vol 2 (S239) ◽

pp. 157-159

Author(s):

John Southworth ◽

Hans Bruntt

Keyword(s):

Binary Stars ◽

Eclipsing Binaries ◽

Eclipsing Binary ◽

Fundamental Properties ◽

Eclipsing Binary Stars ◽

Average System ◽

Stellar Models

AbstractThe fundamental properties of detached eclipsing binary stars can be measured very accurately, which could make them important objects for constraining the treatment of convection in theoretical stellar models. However, only four or five pieces of information can be found for the average system, which is not enough. We discuss studies of more interesting and useful objects: eclipsing binaries in clusters and eclipsing binaries with pulsating components.

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K2-97b: A (RE-?)INFLATED PLANET ORBITING A RED GIANT STAR

The Astronomical Journal ◽

10.3847/0004-6256/152/6/185 ◽

2016 ◽

Vol 152 (6) ◽

pp. 185 ◽

Cited By ~ 38

Author(s):

Samuel K. Grunblatt ◽

Daniel Huber ◽

Eric J. Gaidos ◽

Eric D. Lopez ◽

Benjamin J. Fulton ◽

...

Keyword(s):

Giant Star ◽

Red Giant

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Eclipsing spotted giant star with K2 and historical photometry

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834106 ◽

2018 ◽

Vol 620 ◽

pp. A189 ◽

Cited By ~ 3

Author(s):

K. Oláh ◽

S. Rappaport ◽

T. Borkovits ◽

T. Jacobs ◽

D. Latham ◽

...

Keyword(s):

Binary System ◽

Main Sequence ◽

Rapid Evolution ◽

Magnetic Activity ◽

Primary Component ◽

Physical Parameters ◽

Giant Star ◽

Eclipsing Binary ◽

Giant Stars ◽

Active Stars

Context. Stars can maintain their observable magnetic activity from the pre-main sequence (PMS) to the tip of the red giant branch. However, the number of known active giants is much lower than active stars on the main sequence (MS) since the stars spend only about 10% of their MS lifetime on the giant branch. Due to their rapid evolution it is difficult to estimate the stellar parameters of giant stars. A possibility for obtaining more reliable stellar parameters for an active giant arises when it is a member of an eclipsing binary system. Aims. We have discovered EPIC 211759736, an active spotted giant star in an eclipsing binary system during the Kepler K2 Campaign 5. The eclipsing nature allows us to much better constrain the stellar parameters than in most cases of active giant stars. Methods. We have combined the K2 data with archival HATNet, ASAS, and DASCH photometry, new spectroscopic radial velocity measurements, and a set of follow-up ground-based BVRCIC photometric observations, to find the binary system parameters as well as robust spot models for the giant at two different epochs. Results. We determined the physical parameters of both stellar components and provide a description of the rotational and long-term activity of the primary component. The temperatures and luminosities of both components were examined in the context of the Hertzsprung–Russell diagram. We find that both the primary and the secondary components deviate from the evolutionary tracks corresponding to their masses in the sense that the stars appear in the diagram at lower masses than their true masses. Conclusions. We further evaluate the proposition that traditional methods generally result in higher masses for active giants than what is indicated by stellar evolution tracks in the HR diagram. A possible reason for this discrepancy could be a strong magnetic field, since we see greater differences in more active stars.

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