scholarly journals WASP 0639-32: a new F-type subgiant/K-type main-sequence detached eclipsing binary from the WASP project

2018 ◽  
Vol 615 ◽  
pp. A135 ◽  
Author(s):  
J. A. Kirkby-Kent ◽  
P. F. L. Maxted ◽  
A. M. Serenelli ◽  
D. R. Anderson ◽  
C. Hellier ◽  
...  
Keyword(s):  
Binary System ◽  
Main Sequence ◽  
Mass Density ◽  
Helium Abundance ◽  
Eclipsing Binary ◽  
Abundance Estimate ◽  
Secondary Star ◽  
Free Parameters ◽  
Effective Temperatures ◽  
The Masses

Aims. Our aim is to measure the masses and radii of the stars in a newly-discovered detached eclipsing binary system to a high precision (≈1%), enabling the system to be used for the calibration of free parameters in stellar evolutionary models. Methods. Photometry from the Wide Angle Search for Planets (WASP) project was used to identify 1SWASP J063930.33-322404.8 (TYC 7091-888-1, WASP 0369-32 hereafter) as a detached eclipsing binary system with total eclipses and an orbital period of P = 11.66 days. Lightcurve parameters for WASP 0639-32 are obtained using the EBOP lightcurve model, with standard errors evaluated using a prayer-bead algorithm. Radial velocities were measured from 11 high-resolution spectra using a broadening function approach, and an orbit was fitted using SBOP. Observed spectra were disentangled and an equivalent width fitting method was used to obtain effective temperatures and metallicities for both stars. A Bayesian framework is used to explore a grid of stellar evolution models, where both helium abundance and mixing length are free to vary, and use observed parameters (mass, density, temperature, and metallicity) for each star to obtain the age and constrain the helium abundance of the system. Results. The masses and radii are found to be M1 = 1.1544 ± 0.0043 M⊙, R1 = 1.833 ± 0.023 R⊙, and M2 = 0.7833 ± 0.0028 M⊙, R2 = 0.7286 ± 0.0081 R⊙ for the primary and secondary, respectively. The effective temperatures were found to be T1 = 6330 ± 50 K and T2 = 5400 ± 80 K for the primary and secondary star, respectively. The system has an age of 4.2−0.1+0.8 Gyr, and a helium abundance in the range 0.251–0.271. Conclusions. WASP 0639-32 is a rare example of a well-characterised detached eclipsing binary system containing a star near the main-sequence turn-off point. This makes it possible to measure a precise age for the stars in this binary system and to estimate their helium abundance. Further work is needed to explore how this helium abundance estimate depends on other free parameters in the stellar models.

scholarly journals Calibration of the Pre-Main Sequence Binary System RS Cha: Impact of the Initial Chemical Mixture

2006 ◽  
Vol 2 (S240) ◽  
pp. 652-657
Author(s):  
E. Alecian ◽  
Y. Lebreton ◽  
M.-J. Goupil ◽  
M.-A. Dupret ◽  
C. Catala
Keyword(s):  
Binary System ◽  
Main Sequence ◽  
Reaction Rates ◽  
Helium Abundance ◽  
Chemical Mixture ◽  
Spectroscopic Binary ◽  
Initial Chemical Composition ◽  
Effective Temperatures ◽  
Stellar Models ◽  
The Impact

AbstractAccurate observational data are available for the eclipsing double-lined spectroscopic binary system RS Cha, composed of two stars in the pre-main sequence stage of evolution: masses, radii, luminosities and effective temperatures of each component and metallicity of the system. This allows to build pre-main sequence stellar models representing the components of RS Cha and to constrain them in terms of physical ingredients, initial chemical composition and age.We present stellar models we have calculated using the CESAM stellar evolution code for different sets of physical inputs (opacities, nuclear reaction rates, etc.) and different initial parameters (global metallicity, helium abundance, individual abundances of heavy elements). We discuss their ability to reproduce the observational constraints simultaneously for the two components. We focus on the impact on the models of the chemical mixture adopted and we propose a calibration for the RS Cha system providing an estimate of its age and initial helium abundance.

scholarly journals Eclipsing spotted giant star with K2 and historical photometry

2018 ◽  
Vol 620 ◽  
pp. A189 ◽  
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.

scholarly journals Mon-735: a new low-mass pre-main-sequence eclipsing binary in NGC 2264

2020 ◽  
Vol 495 (2) ◽  
pp. 1531-1548
Author(s):  
Edward Gillen ◽  
Lynne A Hillenbrand ◽  
John Stauffer ◽  
Suzanne Aigrain ◽  
Luisa Rebull ◽  
...  
Keyword(s):  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Centre Of Mass ◽  
M Dwarfs ◽  
Eclipsing Binary ◽  
Star Forming ◽  
Low Mass ◽  
Effective Temperatures

ABSTRACT We present Mon-735, a detached double-lined eclipsing binary (EB) member of the ∼3 Myr old NGC 2264 star-forming region, detected by Spitzer. We simultaneously model the Spitzer light curves, follow-up Keck/HIRES radial velocities, and the system’s spectral energy distribution to determine self-consistent masses, radii, and effective temperatures for both stars. We find that Mon-735 comprises two pre-main-sequence M dwarfs with component masses of M = 0.2918 ± 0.0099 and 0.2661 ± 0.0095 M⊙, radii of R = 0.762 ± 0.022 and 0.748 ± 0.023 R⊙, and effective temperatures of Teff = 3260 ± 73 and 3213 ± 73 K. The two stars travel on circular orbits around their common centre of mass in P = 1.9751388 ± 0.0000050 d. We compare our results for Mon-735, along with another EB in NGC 2264 (CoRoT 223992193), to the predictions of five stellar evolution models. These suggest that the lower mass EB system Mon-735 is older than CoRoT 223992193 in the mass–radius diagram (MRD) and, to a lesser extent, in the Hertzsprung–Russell diagram (HRD). The MRD ages of Mon-735 and CoRoT 223992193 are ∼7–9 and 4–6 Myr, respectively, with the two components in each EB system possessing consistent ages.

scholarly journals Light curve analysis of the eclipsing binary system V781 Tau

2021 ◽  
Vol 2145 (1) ◽  
pp. 012005
Author(s):  
N Lamlert ◽  
W Maithong
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Orbital Period ◽  
Binary Systems ◽  
Curve Analysis ◽  
Photometric System ◽  
Light Curve Analysis ◽  
Eclipsing Binary ◽  
The Public ◽  
Secondary Star

Abstract V781 Tau is one of W UMa eclipsing binary systems whose orbital period is 0.34 days. The 0.7-meter telescope with CCD photometric system in B and V filters was conducted at the Regional Observatory for the Public, Chachoengsao, Thailand during December 2018, UT. The Wilson-Devinney Technique was used for calculating the physical properties of V781 Tau. The results showed the inclination of their orbital is 66.140°±0.14. The effective temperature of the primary and secondary star is 6,060 and 5,881 K, respectively and the degree of contact is 4.38 %

KIC 5359678: A detached eclipsing binary with starspots

2021 ◽  
Author(s):  
Jiaxin Wang ◽  
Jianning Fu ◽  
Hubiao Niu ◽  
Yang Pan ◽  
Chunqian Li ◽  
...  
Keyword(s):  
Main Sequence ◽  
Function Analysis ◽  
Light Curves ◽  
Main Sequence Stars ◽  
Period Range ◽  
Eclipsing Binary ◽  
A Value ◽  
Auto Correlation ◽  
Auto Correlation Function ◽  
The Masses

Abstract We study the detached eclipsing binary, KIC 5359678, with starspot modulation using the high-quality Kepler photometry and LAMOST spectroscopy. The PHOEBE model, optimal for this binary, reveals that this system is a circular detached binary, composed of two F-type main-sequence stars. The masses and radii of the primary and the secondary are M1 = 1.31 ± 0.05M⊙, R1 = 1.52 ± 0.04R⊙, M2 = 1.12 ± 0.04M⊙, and R2 = 1.05 ± 0.06R⊙, respectively. The age of this binary is estimated to be about 2Gyr, a value much longer than the synchronization timescale of 17.8 Myr. The residuals of light curves show quasi-sinusoidal signals, which could be induced by starspots. We apply auto-correlation function analysis on the out-of-eclipse residuals and find that the spot with rotational period close to the orbital period, while, the decay timescale of starspots is longer than that on the single stars with the same temperature, period range, and rms scatter. A two-starspot model is adopted to fit the signals with two-dip pattern, whose result shows that the longitude decreases with time.

scholarly journals The TESS light curve of AI Phoenicis

2020 ◽  
Vol 498 (1) ◽  
pp. 332-343 ◽  
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.

scholarly journals Fundamental properties of the pre-main sequence eclipsing stars of MML 53 and the mass of the tertiary

2019 ◽  
Vol 623 ◽  
pp. A23 ◽  
Author(s):  
Y. Gómez Maqueo Chew ◽  
L. Hebb ◽  
H. C. Stempels ◽  
A. Paat ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Close Binary ◽  
Formation Mechanisms ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Secondary Star ◽  
The Third ◽  
Eclipsing Stars ◽  
Systemic Velocity ◽  
Outer Component ◽  
The Masses

We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (with PEB = 2.097892 d), and for the first time, confirm the bound-nature of the third star (in a P3 ∼ 9 yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880 ± 100 K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M1 = 1.0400 ± 0.0067 M⊙ and M2 = 0.8907 ± 0.0058 M⊙), their radii within 4.5% (R1 = 1.283 ± 0.043 R⊙ and R2 = 1.107 ± 0.049 R⊙), and the temperature of the secondary star (Teff, 2 = 4379 ± 100 K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7 M⊙ (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16 ± 2 Myr). At this age, the tightening of the MML 53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars’ evolution. The eclipsing components of MML 53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04 M⊙ primary star of MML 53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsing stars of MML 53 are found to be larger but not cooler than predicted by non-magnetic models, it is not clear what is the mechanism that is causing the radius inflation given that activity, spots and/or magnetic fields slowing their contraction, require the inflated stars to be cooler to remain in thermal equilibrium.

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

2019 ◽  
Vol 488 (4) ◽  
pp. 4520-4525 ◽  
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.

scholarly journals Fundamental properties of the pre-main sequence eclipsing stars of MML 53 and the mass of the tertiary

2019 ◽  
Vol 623 ◽  
pp. A23
Author(s):  
Y. Gómez Maqueo Chew ◽  
L. Hebb ◽  
H. C. Stempels ◽  
A. Paat ◽  
K. G. Stassun ◽  
...  
Keyword(s):  
Close Binary ◽  
Formation Mechanisms ◽  
Primary Star ◽  
Eclipsing Binary ◽  
Secondary Star ◽  
The Third ◽  
Eclipsing Stars ◽  
Systemic Velocity ◽  
Outer Component ◽  
The Masses

We present the most comprehensive analysis to date of the Upper Centaurus Lupus eclipsing binary MML 53 (with PEB = 2.097892 d), and for the first time, confirm the bound-nature of the third star (in a P3 ∼ 9 yr orbit) by constraining its mass dynamically. Our analysis is based on new and archival spectra and time-series photometry, spanning 80% of one orbit of the outer component. From the spectroscopic analysis, we determined the temperature of the primary star to be 4880 ± 100 K. The study of the close binary incorporated treatment of spots and dilution by the tertiary in the light curves, allowing for the robust measurement of the masses of the eclipsing components within 1% (M1 = 1.0400 ± 0.0067 M⊙ and M2 = 0.8907 ± 0.0058 M⊙), their radii within 4.5% (R1 = 1.283 ± 0.043 R⊙ and R2 = 1.107 ± 0.049 R⊙), and the temperature of the secondary star (Teff, 2 = 4379 ± 100 K). From the analysis of the eclipse timings, and the change in systemic velocity of the eclipsing binary and the radial velocities of the third star, we measured the mass of the outer companion to be 0.7 M⊙ (with a 20% uncertainty). The age we derived from the evolution of the temperature ratio between the eclipsing components is fully consistent with previous, independent estimates of the age of Upper Centaurus Lupus (16 ± 2 Myr). At this age, the tightening of the MML 53 eclipsing binary has already occurred, thus supporting close-binary formation mechanisms that act early in the stars’ evolution. The eclipsing components of MML 53 roughly follow the same theoretical isochrone, but appear to be inflated in radius (by 20% for the primary and 10% for the secondary) with respect to recent evolutionary models. However, our radius measurement of the 1.04 M⊙ primary star of MML 53 is in full agreement with the independent measurement of the secondary of NP Per which has the same mass and a similar age. The eclipsing stars of MML 53 are found to be larger but not cooler than predicted by non-magnetic models, it is not clear what is the mechanism that is causing the radius inflation given that activity, spots and/or magnetic fields slowing their contraction, require the inflated stars to be cooler to remain in thermal equilibrium.

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