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

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/202039250 ◽

2020 ◽

Vol 645 ◽

pp. A25

Author(s):

K. Brogaard ◽

E. Pakštienė ◽

F. Grundahl ◽

Š. Mikolaitis ◽

G. Tautvaišienė ◽

...

Keyword(s):

Binary Stars ◽

Giant Star ◽

Eclipsing Binary ◽

Helium Content ◽

Additional Information ◽

Red Giant ◽

Model Dependency ◽

The Masses ◽

Cluster Age ◽

Age Estimates

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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DISCOVERY OF A RED GIANT WITH SOLAR-LIKE OSCILLATIONS IN AN ECLIPSING BINARY SYSTEM FROM KEPLER SPACE-BASED PHOTOMETRY

The Astrophysical Journal ◽

10.1088/2041-8205/713/2/l187 ◽

2010 ◽

Vol 713 (2) ◽

pp. L187-L191 ◽

Cited By ~ 56

Author(s):

S. Hekker ◽

J. Debosscher ◽

D. Huber ◽

M. G. Hidas ◽

J. De Ridder ◽

...

Keyword(s):

Binary System ◽

Eclipsing Binary ◽

Red Giant

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Symbiotic Eclipsing Binary Star CI CYG. The Cold Component Variability

International Astronomical Union Colloquium ◽

10.1017/s0252921100103409 ◽

1988 ◽

Vol 103 ◽

pp. 197-197

Author(s):

T.S. Belyakina

Keyword(s):

Binary System ◽

Variable Star ◽

Binary Star ◽

Time Interval ◽

Temperature Variations ◽

Eclipsing Binary ◽

Cold Component ◽

Red Giant ◽

Eclipsing Binary Star

AbstractIt has been shown that the cold component of CI Cyg eclipsing binary system is a variable star. The amplitude of its light variations is close to with the time interval of 40–60 days.This star being the red giant M4 can be attributed as SR type variability. The light variations is caused by its temperature variations.

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Discovery of a stripped red giant core in a bright eclipsing binary system★

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2011.19567.x ◽

2011 ◽

Vol 418 (2) ◽

pp. 1156-1164 ◽

Cited By ~ 45

Author(s):

P. F. L. Maxted ◽

D. R. Anderson ◽

M. R. Burleigh ◽

A. Collier Cameron ◽

U. Heber ◽

...

Keyword(s):

Binary System ◽

Eclipsing Binary ◽

Red Giant

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Response to Comment on “A noninteracting low-mass black hole–giant star binary system”

Science ◽

10.1126/science.aba4356 ◽

2020 ◽

Vol 368 (6491) ◽

pp. eaba4356 ◽

Cited By ~ 2

Author(s):

Todd A. Thompson ◽

Christopher S. Kochanek ◽

Krzysztof Z. Stanek ◽

Carles Badenes ◽

Tharindu Jayasinghe ◽

...

Keyword(s):

Black Hole ◽

Binary System ◽

Triple System ◽

Solar Mass ◽

Giant Star ◽

Low Mass ◽

Red Giant ◽

Star Binary ◽

Existing Data

Van den Heuvel and Tauris argue that if the red giant star in the system 2MASS J05215658+4359220 has a mass of 1 solar mass (M☉), then its unseen companion could be a binary composed of two 0.9 M☉ stars, making a triple system. We contend that the existing data are most consistent with a giant of mass 3.2−1.0+1.0M☉, implying a black hole companion of 3.3−0.7+2.8M☉.

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X-ray and UV emission of the ultrashort-period, low-mass eclipsing binary system BX Trianguli

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834116 ◽

2018 ◽

Vol 619 ◽

pp. A138

Author(s):

V. Perdelwitz ◽

S. Czesla ◽

J. Robrade ◽

T. Pribulla ◽

J. H. M. M. Schmitt

Keyword(s):

Binary System ◽

Light Curve ◽

Binary Systems ◽

Uv Light ◽

Close Binary ◽

Eclipsing Binary ◽

X Ray ◽

Uv Emission ◽

Low Mass ◽

Orbital Modulation

Context.Close binary systems provide an excellent tool for determining stellar parameters such as radii and masses with a high degree of precision. Due to the high rotational velocities, most of these systems exhibit strong signs of magnetic activity, postulated to be the underlying reason for radius inflation in many of the components. Aims.We extend the sample of low-mass binary systems with well-known X-ray properties. Methods.We analyze data from a singular XMM-Newton pointing of the close, low-mass eclipsing binary system BX Tri. The UV light curve was modeled with the eclipsing binary modeling tool PHOEBE and data acquired with the EPIC cameras was analyzed to search for hints of orbital modulation. Results.We find clear evidence of orbital modulation in the UV light curve and show that PHOEBE is fully capable of modeling data within this wavelength range. Comparison to a theoretical flux prediction based on PHOENIX models shows that the majority of UV emission is of photospheric origin. While the X-ray light curve does exhibit strong variations, the signal-to-noise ratio of the observation is insufficient for a clear detection of signs of orbital modulation. There is evidence of a Neupert-like correlation between UV and X-ray data.

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New Data on the Eclipsing Binary V1848 Ori and Improved Orbital and Light Curve Solutions

Open Astronomy ◽

10.1515/astro-2020-0013 ◽

2020 ◽

Vol 29 (1) ◽

pp. 72-80 ◽

Cited By ~ 1

Author(s):

Fatemeh Davoudi ◽

Atila Poro ◽

Fahri Alicavus ◽

Afshin Halavati ◽

Saeed Doostmohammadi ◽

...

Keyword(s):

Binary System ◽

Light Curve ◽

Mass Function ◽

Light Curves ◽

Complete Analysis ◽

Physical Parameters ◽

Mass Ratio ◽

Third Body ◽

Eclipsing Binary

AbstractNew observations of the eclipsing binary system V1848 Ori were carried out using the V filter resulting in a determination of new times of minima and new ephemeris were obtained. We presented the first complete analysis of the system’s orbital period behavior and analysis of O-C diagram done by the GA and MCMC approaches in OCFit code. The O-C diagram demonstrates a sinusoidal trend in the data; this trend suggests a cyclic change caused by the LITE effect with a period of 10.57 years and an amplitude of 7.182 minutes. It appears that there is a third body with mass function of f (m3) = 0.0058 M⊙ in this binary system. The light curves were analyzed using the Wilson-Devinney code to determine some geometrical and physical parameters of the system. These results show that V1848 Ori is a contact W UMa binary system with the mass ratio of q = 0.76 and a weak fillout factor of 5.8%. The O’Connell effect was not seen in the light curve and there is no need to add spot.

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