Article

Empirical bolometric correction coefficients for nearby main-sequence stars in the Gaia era

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Abstract

Nearby detached double-lined eclipsing binaries with most accurate data were studied and 290 systems were found with at least one main-sequence component having a metallicity of 0.008 ≤ Z ≤ 0.040. Stellar parameters, light ratios, Gaia Data Release 2 trigonometric parallaxes, extinctions and/or reddening were investigated and only 206 systems were selected as eligible to calculate empirical bolometric corrections. NASA/IPAC Galactic dust maps were the main source of extinctions. Unreliable extinctions at low Galactic latitudes |b| ≤ 5° were replaced with individual determinations, if they exist in the literature, else associated systems were discarded. The main-sequence stars of te remaining systems were used to calculate the bolometric corrections (BCs) and to calibrate the BC–Teff relation, which is valid in the range 3100–36 000 K. De-reddened (B − V)0 colours, on the other hand, allowed us to calibrate two intrinsic colour–effective temperature relations; the linear one is valid for $T_{\rm eff}\gt 10\, 000$ K, while the quadratic relation is valid for $T_{\rm eff}\lt 10\, 000$ K; that is, both are valid in the same temperature range in which the BC–Teff relation is valid. New BCs computed from Teff and other astrophysical parameters are tabulated, as well.

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... We use the W-D code combined with the MC simulation to reduce degeneration in the solution space and determine the uncertainties of the adjustable parameters (Zola et al. 2004(Zola et al. , 2010. The free parameters in MC and their ranges are given in the Table 2. Thus, the effective temperature of the primary component, T1 was assumed as 5559 K (Eker et al. 2020). This temperature value is a good approximation because we can compare it with that from the Gaia DR2 3 catalog which is 5498 K; Based on the Gaia color BP-RP, the difference in temperature is consistent. ...
... The absolute parameters of BQ Ari are calculated and given in Table 4. The mass of the primary component is derived from a study by Eker et al. (2020), and the mass of the secondary component is calculated based on the value of . Since the radial velocity is not yet available, we were unable to determine the masses of the components with high precision through photometry; we are only able to make reliable estimates here. ...
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The first complete analysis of the photometric observation of the W UMa type binary system BQ Ari was performed using the Wilson-Devinney code to determine its photometric and geometric elements. These results show that BQ Ari is a contact W UMa binary system with a photometric mass ratio q = 0.91, and the fillout factor equal to 34 percent. We calculated the distance of BQ Ari to be 146.24 \pm 15 parsec. In this study, we suggested a new linear ephemeris for BQ Ari, combining our new mid-eclipse times and the previous observations. We present the first complete analysis of the system's orbital period behavior and analysis of the O-C diagram using the Genetic Algorithm (GA) and the Monte Carlo Markov Chain (MCMC) approaches in OCFit code. We applied two approaches to analyze the sinusoidal trend in the O-C diagram. This may suggest a periodic change caused by the Light-Time Effect (LiTE) effect with a period of 4.60 years and an amplitude of 6.212 minutes. On the other hand, the sinusoidal trend may indicate the existence of magnetic activity in this system. The period of magnetic activity was calculated to be 4.16 years and changes of period induced by magnetic activity obtained as DeltaP/P=4.36x 10^(-7). It was concluded that magnetic activity is more likely to be the causal agent as opposed to the LiTE signals.
... The observed colors of IO Cep and IM Cep are kept as they are. In Table 3, we give the photometric colors of the systems and the corresponding temperatures which are adopted from Eker et al. (2020). ...
... The total absolute magnitude of the system is obtained by using the distance and IS absorption ( = 3.1 ( − )) using the distance modulus. After obtaining the absolute magnitude of the components with the light contribution of each component (see Table 4), the bolometric brightness of the components is obtained by using the bolometric corrections (BC) given by Eker et al. (2020). From the bolometric magnitudes, the absolute radius of each component is derived. ...
Article
Three Algol-type binary systems (IO Cep, IM Cep and TX Ari) showing cyclic orbital period changes are studied. The combination of time of minimum data from the ground-based observations together with high precision photometric data from the TESS satellite enabled us to estimate the basic light curve elements of binary systems and mass functions for distant components around the systems. The relation of mass ratio to the system geometry in semi-detached binary stars allowed us to determine the mass ratio of the binary components without using spectra. By using the color and distance information from the GAIA EDR3 and light contributions of the components from the light curve analysis, the astrophysical parameters of the binary components as well as the minimum masses of the distant components are obtained with an uncertainty of ∼10-20 per cent indicating that the method can be a good guide for those studying with faint systems where spectra with sufficient resolution and S/N ratio are difficult to acquire.
... So we used this method to search mass ratio. The free parameters in MC simulation and their ranges are given in Table 3. Eker et al. (2020), the effective temperature of the primary component was found to be 5873 K. Thus, this temperature value is close to the value as the Gaia DR2 catalog (5874 K). As shown in Figure 2, the obtained temperature from derived ( − ) color for the primary component of BO Ari is also in an acceptable range with the method of Sekiguchi and Fukugita (2000). ...
... We estimated the binary system distance using the results of absolute parameters. The value of = 10.14 ± 0.005 was calculated from the observational light curve, and = 4.287 ± 0.03 was obtained using = 0.003 according to the Eker et al. (2020). Based on these values, we calculated the binary system's distance to be 142 ± 9 pc, using = 0.09 ± 0.02 (Schlafly and Finkbeiner 2011). ...
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We present new BVR band photometric light curves of BO Aries obtained in 2020 and combined them with the Transiting Exoplanet Survey Satellite (TESS) light curves. We obtained times of minima based on Gaussian and Cauchy distributions and then applied the Monte Carlo Markov Chain (MCMC) method to measure the amount of uncertainty from our CCD photometry and TESS data. A new ephemeris of the binary system was computed employing 204 times of minimum. The light curves were analyzed using the Wilson-Devinney binary code combined with the Monte Carlo (MC) simulation. For this light curve solution, we considered a dark spot on the primary component. We conclude that this binary is an A-type system with a mass ratio of q=0.2074+-0.0001, an orbital inclination of i=82.18+-0.02 deg, and a fillout factor of f=75.7+-0.8%. Our results for the a(Rsun) and q parameters are consistent with the results of the Xu-Dong Zhang and Sheng-Bang Qian (2020) model. The absolute parameters of the two components were calculated and the distance estimate of the binary system was found to be 142+-9 pc.
... So we used this method to search mass ratio. The free parameters in MC simulation and their ranges are given in Table 3. Eker et al. (2020), the effective temperature of the primary component was found to be 5873 K. Thus, this temperature value is close to the value as the Gaia DR2 catalog (5874 K). As shown in Figure 2, the obtained temperature from derived ( − ) color for the primary component of BO Ari is also in an acceptable range with the method of Sekiguchi and Fukugita (2000). ...
... We estimated the binary system distance using the results of absolute parameters. The value of = 10.14 ± 0.005 was calculated from the observational light curve, and = 4.287 ± 0.03 was obtained using = 0.003 according to the Eker et al. (2020). Based on these values, we calculated the binary system's distance to be 142 ± 9 pc, using = 0.09 ± 0.02 (Schlafly and Finkbeiner 2011). ...
Article
Full-text available
We present new BVR band photometric light curves of BO Aries obtained in 2020 and combined them with the Transiting Exoplanet Survey Satellite (TESS) light curves. We obtained times of minima based on Gaussian and Cauchy distributions and then applied the Monte Carlo Markov Chain (MCMC) method to measure the amount of uncertainty from our CCD photometry and TESS data. A new ephemeris of the binary system was computed employing 204 times of minimum. The light curves were analyzed using the Wilson-Devinney binary code combined with the Monte Carlo (MC) simulation. For this light curve solution, we considered a dark spot on the primary component. We conclude that this binary is an A-type system with a mass ratio of q=0.2074±0.0001, an orbital inclination of i=82.18±0.02 deg, and a fillout factor of f=75.7±0.8%. Our results for the a (R⊙) and q parameters are consistent with the results of the Xu-Dong Zhang and Sheng-Bang Qian (2020) model. The absolute parameters of the two components were calculated and the distance estimate of the binary system was found to be 142±9 pc.
... The metallicities of Czernik 2 and NGC 7654 have not been estimated before. Applying the calibration given by Karaali et al. (2011) on de-reddened TCDs of the two clusters, the metallicities were derived using the normalised UV excesses (δ(U − B) 0.6 ) of the most probable member (P ≥ 0.5) F-G type main-sequence stars within the colour index of 0.3 ≤ (B − V ) 0 ≤ 0.6 mag (Eker et al. 2018(Eker et al. , 2020. ...
Article
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We analysed the open clusters Czernik 2 and NGC 7654 using CCD UBV photometric and Gaia Early Data Release 3 (EDR3) photometric and astrometric data. Structural parameters of the two clusters were derived, including the physical sizes of Czernik 2 being r = 5 and NGC 7654 as 8. We calculated membership probabilities of stars based on their proper motion components as released in the Gaia EDR3. To identify member stars of the clusters, we used these membership probabilities taking into account location and the impact of binarity on main-sequence stars. We used membership probabilities higher than P = 0.5 to identify 28 member stars for Czernik 2 and 369 for NGC 7654. The mean proper motion components (µ α cos δ, µ δ) of Czernik 2 were derived as (−4.03 ± 0.04,−0.99 ± 0.05) mas yr −1 and for NGC 7654 as (−1.89±0.03, −1.20±0.03) mas yr −1. We estimated colour-excesses and metallicities separately using (U − B) × (B − V) two-colour diagrams to derive homogeneously determined parameters. The derived E(B − V) colour excess is 0.46 ± 0.02 mag for Czernik 2 and 0.57 ± 0.04 mag for NGC 7654. [Fe/H] metallic-ities were obtained for the first time for both clusters, −0.08 ± 0.02 dex for Czernik 2 and −0.05 ± 0.01 dex for NGC 7654. Keeping the reddening and metallicity as constant quantities, we fitted PARSEC models using V × (B − V) and V × (U − B) colour-magnitude diagrams, resulting in estimated distance moduli and ages of the two clusters. We obtained the distance modulus for Czernik 2 as 12.80 ± 0.07 mag and for NGC 7654 as 13.20 ± 0.16 mag, which coincide with ages of 1.2 ± 0.2 Gyr and 120 ± 20 Myr, respectively. The distances to the clusters were calculated using the Gaia EDR3 trigonometric parallaxes and compared with the literature. We found good agreement between the distances obtained in this study and the literature. Present-day mass function slopes for both clusters are comparable with the value of Salpeter (1955), being X = −1.37 ± 0.24 for Czernik 2 and X = −1.39 ± 0.19 for NGC 7654.
... LAMOST classifies the spectral type of the detected subgiant as G5. The bolometric correction coefficient (BC) is applied as -0.02 according to the empirical relation for Gaia data (Eker et al. 2020). We use the Vega system for optical magnitude calculations in this work. ...
Preprint
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Single-line spectroscopic binaries recently contribute to the stellar-mass black hole discovery, independently of the X-ray transient method. We report the identification of a single-line binary system LTD064402+245919, with an orbital period of 14.50 days. The observed component is a subgiant with a mass of 2.77$\pm$0.68M$_{\odot}$, radius 15.5$\pm$2.5R$_{\odot}$, effective temperature $T_{\rm eff}$ 4500$\pm$200K, and surface gravity log\emph{g} 2.5$\pm$0.25dex. The discovery makes use of the LAMOST time-domain (LAMOST-TD) and ZTF survey. Our general-purpose software pipeline applies the Lomb-Scargle periodogram to determine the orbital period and uses machine-learning to classify the variable type from the folded light curves. We apply a combined model to estimate the orbital parameters from both the light and radial velocity curves, taking constraints on the primary star mass, mass function, and detection limit of secondary luminosity into consideration. We obtain a radial velocity semi-amplitude of 44.6$\pm$1.5 km s$^{-1}$, mass ratio of 0.73$\pm$0.07, and an undetected component mass of 2.02$\pm$0.49M$_{\odot}$ when the type of the undetected component is not set. We conclude that the inclination is not well constrained, and that the secondary mass is larger than 1M$_{\odot}$ when the undetected component is modelled as a compact object. According to our investigations using an MCMC simulation, increasing the spectra SNR by a factor of 3 would enable the secondary light to be distinguished (if present). The algorithm and software in this work are able to serve as general-purpose tools for the identification of compact objects quiescent in X-rays.
... Calculating the temperatures of components of each system enables us to determine the spectral types and intrinsic colours of the components. By using Solar absolute visual magnitude (4.75 mag) and bolometric corrections from Eker et al. (2020), bolometric magnitudes and absolute magnitudes of the components of each system have been derived. Thus, photometric distances of each system have been carried out using the distance modulus. ...
Preprint
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We present the evolutionary scenarios for three eclipsing twin ($q(M_2/M_1)\sim$1) binary systems using their combined spectroscopic and photometric data. Using accurate \textit{TESS} photometric data, RV measurements, and spectroscopic data enabled us to calculate fundamental parameters, such as mass and radius, better than 2 percent. The temperature of each component and metallicity of the systems have been obtained via high-resolution spectra. According to our spectral analysis, the metallicity values of AN Cam, RS Ari, and V455 Aur are \text{[M/H]}=\,0.00$\pm$0.12, 0.05$\pm$0.08, and -0.07$\pm$0.07, respectively. Using the derived metallicity for each system, initial orbital parameters and detailed evolutionary status of these three systems are calculated with high precision by using \textsc{mesa}. According to our analysis, both components of AN Cam have passed the terminal age main-sequence, the primary component of RS Ari is in the giant phase while the secondary component has passed the terminal age main-sequence, finally, both components of V455 Aur are still on the main-sequence. The current ages of the three systems AN Cam, RS Ari, and V455 Aur are 3.0, 3.3, and 1.4 Gyrs, respectively, and they will approximately start to transfer mass between components in 400, 250, and 2700 Myrs, respectively.
... LAMOST classifies the spectral type of the detected subgiant as G5. The bolometric correction coefficient is applied as −0.02 according to the empirical relation for Gaia data (Eker et al. 2020). We use the Vega system for optical magnitude calculations in this work. ...
Article
Full-text available
Single-line spectroscopic binaries have recently contributed to stellar-mass black hole discovery, independently of the X-ray transient method. We report the identification of a single-line binary system, LTD064402+245919, with an orbital period of 14.50 days. The observed component is a subgiant with a mass of 2.77 ± 0.68 M ⊙ , radius 15.5 ± 2.5 R ⊙ , effective temperature T eff 4500 ± 200 K, and surface gravity log g 2.5 ± 0.25 dex. The discovery makes use of the Large Sky Area Multi-Object fiber Spectroscopic Telescope time-domain and Zwicky Transient Facility survey. Our general-purpose software pipeline applies a Lomb–Scargle periodogram to determine the orbital period and uses machine learning to classify the variable type from the folded light curves. We apply a combined model to estimate the orbital parameters from both the light and radial velocity curves, taking constraints on the primary star mass, mass function, and detection limit of secondary luminosity into consideration. We obtain a radial velocity semiamplitude of 44.6 ± 1.5 km s ⁻¹ , mass ratio of 0.73 ± 0.07, and an undetected component mass of 2.02 ± 0.49 M ⊙ when the type of the undetected component is not set. We conclude that the inclination is not well constrained, and that the secondary mass is larger than 1 M ⊙ when the undetected component is modeled as a compact object. According to our investigations using a Monte Carlo Markov Chain simulation, increasing the spectra signal-to-noise ratio by a factor of 3 would enable the secondary light to be distinguished (if present). The algorithm and software in this work are able to serve as general-purpose tools for the identification of compact objects quiescent in X-rays.
... The bolometric magnitude (M bol ) of each component of the systems is the result of relation 3, where the bolometric correction (BC) is taken from Eker et al. (2020). ...
Preprint
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New relationships between the orbital period and some parameters of W Ursae Majoris (W UMa) type systems are presented in this study. To investigate the relationships, we calculated the absolute parameters of a sample of 118 systems. For this purpose, we used the parallax values obtained from the Gaia Early Data Release 3 (Gaia EDR3) star catalog for more precise calculations. The other required parameters, including the light curve solutions and the orbital period were derived from previous research. For some relationships, we added 86 systems from another study with an orbital period of less than 0.6 days to our sample, allowing us to increase the number of systems to 204. Therefore, the mass (M) values of each component along with all the other absolute parameters were recalculated for these contact systems. We used the Markov Chain Monte Carlo (MCMC) approach in order to gain the new orbital period-mass relations (P-M) per component, and added the temperature (T) to the process to acquire the new orbital period-temperature (P-T1) relation. We presented the orbital period behavior in terms of log(g) by new relations for each component. We have also obtained a model between the orbital period, the mass of the primary component and temperature (P-M1-T1) using the Artificial Neural Networks (ANN) method. Additionally, we present a model for the relationship between the orbital period and the mass ratio (P-q) by fitting a Multi-Layer Perceptron (MLP) regression model to a sample of the data collected from the literature.
... Calculating the temperatures of components of each system enables us to determine the spectral types and intrinsic colours of the components. By using Solar absolute visual magnitude (4.75 mag) and bolometric corrections from Eker et al. (2020), bolometric magnitudes and absolute magnitudes of the components of each system have been derived. Thus, photometric distances of each system have been carried out using the distance modulus. ...
Article
We present the evolutionary scenarios for three eclipsing twin (q(M2/M1) ∼1) binary systems using their combined spectroscopic and photometric data. Using accurate TESS photometric data, RV measurements, and spectroscopic data enabled us to calculate fundamental parameters, such as mass and radius, better than 2 percent. The temperature of each component and metallicity of the systems have been obtained via high-resolution spectra. According to our spectral analysis, the metallicity values of AN Cam, RS Ari, and V455 Aur are [M/H]= 0.00±0.12, 0.05±0.08, and -0.07±0.07, respectively. Using the derived metallicity for each system, initial orbital parameters and detailed evolutionary status of these three systems are calculated with high precision by using mesa. According to our analysis, both components of AN Cam have passed the terminal age main-sequence, the primary component of RS Ari is in the giant phase while the secondary component has passed the terminal age main-sequence, finally, both components of V455 Aur are still on the main-sequence. The current ages of the three systems AN Cam, RS Ari, and V455 Aur are 3.0, 3.3, and 1.4 Gyrs, respectively, and they will approximately start to transfer mass between components in 400, 250, and 2700 Myrs, respectively.
... The bolometric magnitude (M bol ) of each component of the systems is the result of relation 3, where the bolometric correction (BC) is taken from Eker et al. (2020). ...
Article
Full-text available
New relationships between the orbital period and some parameters of W Ursae Majoris (W UMa) type systems are presented in this study. To investigate the relationships, we calculated the absolute parameters of a sample of 118 systems. For this purpose, we used the parallax values obtained from the Gaia Early Data Release 3 (Gaia EDR3) star catalog for more precise calculations. The other required parameters, including the light curve solutions and the orbital period were derived from previous research. For some relationships, we added 86 systems from another study with an orbital period of less than 0.6 days to our sample, allowing us to increase the number of systems to 204. Therefore, the mass (M) values of each component along with all the other absolute parameters were recalculated for these contact systems. We used the Markov Chain Monte Carlo (MCMC) approach in order to gain the new orbital period-mass relations (P − M) per component, and added the temperature (T) to the process to acquire the new orbital period-temperature (P − T1) relation. We presented the orbital period behaviour in terms of log(g) by new relations for each component. We have also obtained a model between the orbital period, the mass of the primary component and temperature (P − M1 − T1) using the Artificial Neural Networks (ANN) method. Additionally, we present a model for the relationship between the orbital period and the mass ratio (P − q) by fitting a Multi-Layer Perceptron (MLP) regression model to a sample of the data collected from the literature.
... In order to determine the photometric metallicities we employed the method of Karaali et al. (2011), which is based on F-and G-type main-sequence stars and their UV excesses. We calculated the intrinsic (B − V ) 0 and (U − B) 0 colors of the most likely members (P 0.5) and made a selection of mainsequence stars considering the 0.3 (B − V ) 0 0.6 mag range (Eker et al. 2020(Eker et al. , 2018 which corresponds to F-and G-type main-sequence stars. Plotting the (U − B) 0 × (B − V ) 0 TCDs of the selected stars and the Hyades main sequence, we calculated the difference between the (U − B) 0 color indices of the member stars and the Hyades stars, which is defined as the UV excess (δ). ...
Article
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This study calculated astrophysical parameters, as well as kinematic and galactic orbital parameters, of the open clusters NGC 1664 and NGC 6939. The work is based on CCD ultraviolet, blue, and visual (UBV) and Gaia photometric and astrometric data from ground- and space-based observations. Considering Gaia Early Data Release 3 (EDR3) astrometric data, we determined membership probabilities of stars located in both of the clusters. We used two-color diagrams to determine the E ( B − V ) color excesses for NGC 1664 and NGC 6939 as 0.190 ± 0.018 and 0.380 ± 0.025 mag, respectively. Photometric metallicities for the two clusters were estimated as [Fe/H] = −0.10 ± 0.02 dex for NGC 1664 and as [Fe/H] = −0.06 ± 0.01 dex for NGC 6939. Using the reddening and metallicity calculated in the study, we obtained distance moduli and ages of the clusters by fitting parsec isochrones to the color–magnitude diagrams based on the most likely member stars. Isochrone fitting distances are 1289 ± 47 pc and 1716 ± 87 pc, which coincide with ages of 675 ± 50 Myr and 1.5 ± 0.2 Gyr for NGC 1664 and NGC 6939, respectively. We also derived the distances to the clusters using Gaia trigonometric parallaxes and compared these estimates with the literature. We concluded that the results are in good agreement with those given by the current study. Present-day mass function slopes were calculated as Γ = −1.22 ± 0.33 and Γ = −1.18 ± 0.21 for NGC 1664 and NGC 6939, respectively, which are compatible with the Salpeter slope. Analyzes showed that both of clusters are dynamically relaxed. The kinematic and dynamic orbital parameters of the clusters were calculated, indicating that the birthplaces of the clusters are outside the solar circle.
... where V is the visual magnitude, d is the distance of the systems. After the M V values were derived the M bol parameters were computed taking into account the TIC T eff values and bolometric corrections from Eker et al. (2020). If there is no T eff value for a system we estimated this value from the target's spectral type by using the calibration between the spectral type and T eff given by Gray (1992). ...
Preprint
Existence of pulsating stars in eclipsing binaries has been known for decades. These types of objects are extremely valuable systems for astronomical studies as they exhibit both eclipsing and pulsation variations. The eclipsing binaries are the only way to directly measure the mass and radius of stars with a good accuracy ($\leq$1\%), while the pulsations are a unique way to probe the stellar interior via oscillation frequencies. There are different types of pulsating stars existing in eclipsing binaries. One of them is the Delta Scuti variables. Currently, the known number of Delta Scuti stars in eclipsing binaries is around 90 according to the latest catalog of these variables. An increasing number of these kinds of variables is important to understand the stellar structure, evolution and the effect of binarity on the pulsations. Therefore, in this study, we focus on discovering new eclipsing binaries with Delta Scuti component(s). We searched for the northern TESS field with a visual inspection by following some criteria such as light curve shape, the existence of pulsation like variations in the out-of-eclipse light curve and the Teff values of the targets. As a result of these criteria, we determined some targets. The TESS light curves of the selected targets first were removed from the binarity and frequency analysis was performed on the residuals. The luminosity, absolute and bolometric magnitudes of the targets were calculated as well. To find how much of these parameters represent the primary binary component (more luminous) we also computed the flux density ratio of the systems by utilizing the area of the eclipses. In addition, the positions of the systems in the H-R diagram were examined considering the flux density ratios. As a consequence of the investigation, we defined 38 candidates Delta Scuti and also one Maia variable in eclipsing binary systems.
... Determined spectral types from the analyzed photometric data and temperatures, which calculated fromEker et al. (2020). The full table is available online. ...
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49 new eclipsing twin binary candidates are identified and analyzed based on Kepler eclipsing binary light curves. Their colours and spectral types are calculated according to our classification. A comparison of the spectral type distribution of eclipsing twin binary systems showed that F-type twins dominate among others, which agrees well with recent studies. The distance of eclipsing twin binaries from the galactic plane shows that F and G-type twins can be seen at any distance from the galactic plane and most of the known eclipsing binary twins are located within 200 pc of the galactic plane, which could be interpreted as these systems are members of thin disk population. As a case study, a twin binary system selected from our updated list of twins, V396~Gem, has been analyzed with spectroscopic and Kepler data. As a result, we have derived the physical parameters of the components of V396~Gem as $M_{1,2}(M_\odot)= 1.814\pm0.114$, $1.797\pm0.114$; $R_{1,2}(R_\odot)= 2.655\pm0.078$, $2.659\pm0.090$; $T_{\mathrm{eff}_{1,2}}(K)=7000\pm100$, $6978\pm100$; $[M/H]=0.11\pm0.03$. We have calculated the evolutionary status of the components by using MESA. Accurately derived physical parameters of the components of V396~Gem have allowed us to determine the age of the system as 1.168$\pm$0.149 Byrs.
... In a similar way synthetic IAMS is consistent in a wide mass range but diverges for higher masses, see Fig. 9. For validation we use table 6 from Eker et al. (2020), which is based on empirical relations and provides absolute magnitudes for MS stars in 0.25 -64 ⊙ range. PARSEC model clearly shows better agreement with empirical data therefore we further rely on it, leaving MIST as an evolutionary phase marker. ...
Preprint
Objects from the Sixth catalog of orbits of visual binary stars (ORB6) are investigated to validate Gaia EDR3 parallaxes and provide mass estimates for the respected systems. We show that 2/3 of binaries with 0.2 -- 0.5 arcsec separation are left without parallax solution in EDR3. A special attention is paid to 521 pairs with parallax known separately for both components. 16 entries are deemed optical pairs. At once we give examples of solid binary stars with large discrepancy of reported parallaxes, which are underestimated at least by a factor of 3 for stars with large RUWE. Parallaxes are needed to estimate stellar masses. Since nearly 30\% of ORB6 entries lack full 5 or 6-parameter solution in EDR3, we attempt to enrich the astrometric data. Distant companions of ORB6 entries are revealed in EDR3 by analysis of stellar proper motion and Hipparcos parallaxes. In certain cases intrinsic EDR3 parallaxes of binary components are less reliable than of the outer companions. Gaia DR2, TGAS and Hipparcos parallaxes are used when EDR3 data is unavailable. Synthetic mass-luminosity relation in G band for main sequence stars is obtained to provide mass estimates along with dynamical mass calculated via Kepler's Third Law.
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Arbitrariness attributed to the zero point constant of the V band bolometric corrections (BCV) and its relation to “bolometric magnitude of a star ought to be brighter than its visual magnitude” and “bolometric corrections must always be negative” was investigated. The falsehood of the second assertion became noticeable to us after IAU 2015 General Assembly Resolution B2, where the zero point constant of bolometric magnitude scale was decided to have a definite value CBol(W) = 71.197 425 ... . Since the zero point constant of the BCV scale could be written as C2 = CBol − CV, where CV is the zero point constant of the visual magnitudes in the basic definition BCV = MBol − MV = mbol − mV, and CBol > CV, the zero point constant (C2) of the BCV scale cannot be arbitrary anymore; rather, it must be a definite positive number obtained from the two definite positive numbers. The two conditions C2 > 0 and 0 < BCV < C2 are also sufficient for LV < L, a similar case to negative BCV numbers, which means that “bolometric corrections are not always negative”. In sum it becomes apparent that the first assertion is misleading causing one to understand bolometric corrections must always be negative, which is not necessarily true.
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Context. The Bp star HD 94660 is a single-lined spectroscopic binary. Some authors have suggested that the unseen companion of at least 2 M ⊙ may be a compact object. Aims. We intend to study this multiple system in detail, especially to learn more about the thus far unseen companion. Methods. We have collected and analyzed PIONIER (Precision Integrated-Optics Near-infrared Imaging ExpeRiment) H -band data from the Very Large Telescope Interferometer, TESS (Transiting Exoplanet Survey Satellite) visible photometric data, and X-ray observations with Chandra of HD 94660. Results. Using PIONIER, we were able to detect the companion to HD 94660, which is absent from high quality spectra at visible wavelengths, with a magnitude difference of 1.8 in the H band at a separation of 18.72 mas. The TESS light curve shows variations with a period of 2.1 d and also flaring. The Chandra spectrum is well described by emission from hot thermal plasma, yet it might include a nonthermal component. The X-ray properties are compatible with a magnetically active companion, while it is also possible that there might be some magnetospheric contributions from the primary. Conclusions. We can rule out that the companion to HD 94660 is a compact source. It is also very unlikely that this companion is a single star, as the estimated mass of more than 2 M ⊙ , the magnitude difference of 1.8 in the H band, and its nondetection in visible spectra are difficult to realize in a single object. One alternative could be a pair of late F stars, which would also be responsible for the detected photometric variations. Interferometric observations over the full binary orbit are necessary to determine the real mass of the companion and to add constraints on the overall geometry of the system.
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Analysis of timing variation of the eclipsing binary RR Dra implies the existence of an additional object with mass of no less than 3.5(±0.2) M⊙. This third object is orbiting around the central eclipsing pair once every 98(±1) years, making the whole a hierarchical triple system. However, reliable photometric solutions based on light curves from TESS and WASP show that contribution of the third-light takes only about 2% of the total luminosity. It could photometrically be attributed to other unrelated star located within the aperture. The tertiary component is thus a massive object but invisible in optical wavelengths. Besides, evidence of misalignment between the barycenter and the center of light of the system is also found. This strengthen the existence of a hidden black hole candidate in the form of the third body. The potential black hole may play an essential role in extracting angular momentum from the central binary pair, forming the current state. As a good laboratory, RR Dra is an interesting system that can help to study stellar-mass black hole under the circumbinary case.
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New CCD photometric observations and their investigation of the W UMa-type binary, V870 Ara, are presented. Light curves of the system taken in BVI filters from Congarinni Observatory in Australia. The new ephemeris is calculated based on seven new determined minima times together with the TESS data and others compiled from the literature. Photometric solutions determined with the Wilson-Devinney (W-D) code combined the Monte Carlo simulation to determine the adjustable parameters' uncertainties. These solutions suggest that V870 Ara is a contact binary system with a mass ratio of 0.244+-0.019, a fillout factor of 69+-4%, and an inclination of 67.53+-0.35 degrees. Absolute parameters of V870 Ara were determined by combining the Gaia EDR3 parallax and photometric elements.
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Methods of obtaining stellar luminosities (L) have been revised and a new concept, standard stellar luminosity, has been defined. In this paper, we study three methods: (i) a direct method from radii and effective temperatures; (ii) a method using a mass–luminosity relation (MLR); and (iii) a method requiring a bolometric correction. If the unique bolometric correction (BC) of a star extracted from a flux ratio (fV/fBol) obtained from the observed spectrum with sufficient spectral coverage and resolution are used, the third method is estimated to provide an uncertainty (ΔL/L) typically at a low percentage, which could be as accurate as 1 per cent, perhaps more. The typical and limiting uncertainties of the predicted L of the three methods were compared. The secondary methods, which require either a pre-determined non-unique BC or MLR, were found to provide less accurate luminosities than the direct method, which could provide stellar luminosities with a typical accuracy of 8.2–12.2 per cent while its estimated limiting accuracy is 2.5 per cent.
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New CCD photometric observations and their investigation of the W UMa-type binary, V870 Ara, are presented. Light curves of the system were taken through BVIfilters from the Congarinni Observatory in Australia. The new ephemeris is calculated based on seven new determined minimum times, together with the TESS data and others compiled from the literature. Photometric solutions determined by the Wilson-Devinney (W-D) code are combined with the Monte Carlo simulation to determine the adjustable parameters’ uncertainties. These solutions suggest that V870 Ara is a contact binary system with a mass ratio of 0.082, a fillout factor of 96±4 percent, and an inclination of 73.60±0.64 degrees. The absolute parameters of V870 Ara were determined by combining the Gaia EDR3 parallax and photometric elements.
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Three Algol-type binary systems (IO Cep, IM Cep and TX Ari) showing cyclic orbital period changes are studied. The combination of time of minimum data from the ground-based observations together with high precision photometric data from the TESS satellite enabled us to estimate the basic light curve elements of binary systems and mass functions for distant components around the systems. The relation of mass ratio to the system geometry in semi-detached binary stars allowed us to determine the mass ratio of the binary components without using spectra. By using the color and distance information from the GAIA EDR3 and light contributions of the components from the light curve analysis, the astrophysical parameters of the binary components as well as the minimum masses of the distant components are obtained with an uncertainty of ~10-20 per cent indicating that the method can be a good guide for those studying with faint systems where spectra with sufficient resolution and S/N ratio are difficult to acquire.
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Gaia stellar measurements are currently revolutionizing our knowledge of the evolutionary history of the Milky Way. 3D maps of the interstellar dust provide complementary information and are a tool for a wide range of uses. We built 3D maps of the dust in the Local arm and surrounding regions. To do so, Gaia DR2 photometric data were combined with 2MASS measurements to derive extinction toward stars that possess accurate photometry and relative uncertainties on DR2 parallaxes smaller than 20%. We applied a new hierarchical inversion algorithm to the individual extinctions that is adapted to large datasets and to an inhomogeneous target distribution. Each step associates regularized Bayesian inversions in all radial directions and a subsequent inversion in 3D of all their results. Each inverted distribution serves as a prior for the subsequent step, and the spatial resolution is progressively increased. We present the resulting 3D distribution of the dust in a 6 × 6 × 0.8 kpc ³ volume around the Sun. Its main features are found to be elongated along different directions that vary from below to above the mid-plane. The outer part of Carina-Sagittarius, mainly located above the mid-plane, the Local arm/Cygnus Rift around and above the mid-plane, and the fragmented Perseus arm are oriented close to the direction of circular motion. The spur of more than 2 kpc length (nicknamed the split ) that extends between the Local Arm and Carina-Sagittarius, the compact near side of Carina-Sagittarius, and the Cygnus Rift below the Plane are oriented along l ~40 to 55°. Dust density images in vertical planes reveal a wavy pattern in some regions and show that the solar neighborhood within ~500 pc remains atypical by its extent above and below the Plane. We show several comparisons with the locations of molecular clouds, HII regions, O stars, and masers. The link between the dust concentration and these tracers is markedly different from one region to the other.
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For the vast majority of stars in the second Gaia data release, reliable distances cannot be obtained by inverting the parallax. A correct inference procedure must instead be used to account for the nonlinearity of the transformation and the asymmetry of the resulting probability distribution. Here, we infer distances to essentially all 1.33 billion stars with parallaxes published in the second Gaia data release. This is done using a weak distance prior that varies smoothly as a function of Galactic longitude and latitude according to a Galaxy model. The irreducible uncertainty in the distance estimate is characterized by the lower and upper bounds of an asymmetric confidence interval. Although more precise distances can be estimated for a subset of the stars using additional data (such as photometry), our goal is to provide purely geometric distance estimates, independent of assumptions about the physical properties of, or interstellar extinction toward, individual stars. We analyze the characteristics of the catalog and validate it using clusters. The catalog can be queried using ADQL at http://gaia.ari.uni-heidelberg.de/tap.html (which also hosts the Gaia catalog) and downloaded from http://www.mpia.de/∼calj/gdr2-distances.html. © 2018. The American Astronomical Society. All rights reserved..
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Gaia is a cornerstone mission in the science programme of the European Space Agency (ESA). The spacecraft construction was approved in 2006, following a study in which the original interferometric concept was changed to a direct-imaging approach. Both the spacecraft and the payload were built by European industry. The involvement of the scientific community focusses on data processing for which the international Gaia Data Processing and Analysis Consortium (DPAC) was selected in 2007. Gaia was launched on 19 December 2013 and arrived at its operating point, the second Lagrange point of the Sun-Earth-Moon system, a few weeks later. The commissioning of the spacecraft and payload was completed on 19 July 2014. The nominal five-year mission started with four weeks of special, ecliptic-pole scanning and subsequently transferred into full-sky scanning mode. We recall the scientific goals of Gaia and give a description of the as-built spacecraft that is currently (mid-2016) being operated to achieve these goals. We pay special attention to the payload module, the performance of which is closely related to the scientific performance of the mission. We provide a summary of the commissioning activities and findings, followed by a description of the routine operational mode. We summarise scientific performance estimates on the basis of in-orbit operations. Several intermediate Gaia data releases are planned and the data can be retrieved from the Gaia Archive, which is available through the Gaia home page at http://www.cosmos.esa.int/gaia.
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We present six new BVRcIc CCD light curves of a short-period RS CVn binary DV Psc obtained in 2010-2012. The light curve distortions change on both short and long timescales, which is explained by two starspots on the primary component. Moreover, five new flare events were detected and the flare ratio of DV Psc is about 0.082 flares per hour. There is a possible relation between the phases (longitude) of the flares and starspots for all of the available data of late-type binaries, which implies a correlation of the stellar activity of the spots and flares. The cyclic oscillation, with a period of 4.9 +/- 0.4 yr, may result from the magnetic activity cycle, identified by the variability of Max. I-Max. II. Until now, there were no spectroscopic studies of chromospheric activity indicators of the H-beta and H-gamma lines for DV Psc. Our observations of these indicators show that DV Psc is active, with excess emissions. The updated O - C diagram with an observing time span of about 15 yr shows an upward parabola, which indicates a secular increase in the orbital period of DV Psc. The orbital period secularly increases at a rate of dP/dt = 2.0x10(-7) days yr(-1), which might be explained by the angular momentum exchanges or mass transfer from the secondary to primary component.
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New high-resolution spectroscopy and BVR photometry, together with literature data, on the Gould's Belt close binary systems GG Lup and μ1 Sco are presented and analysed. In the case of GG Lup, light and radial velocity curve fittings confirm a near-main-sequence picture of a pair of close stars. Absolute parameters are found, to within a few per cent, thus: M1 = 4.16 ± 0.12, M2 = 2.64 ± 0.12 (M⊙); R1 = 2.42 ± 0.05, R2 = 1.79 ± 0.04 (R⊙); T1 ∼ 13 000, T2 ∼ 10 600 (K); photometric distance ∼160 (pc). The high eccentricity and relatively short period (105 yr) of apsidal revolution may be related to an apparent ‘slow B-type pulsator’ oscillation. Disturbances of the outer envelope of at least one of the components then compromise comparisons to standard evolutionary models, at least regarding the age of the system. A rate of apsidal advance is derived, which allows a check on the mean internal structure constant $\overline{k_2} = 0.0058 \pm 0.0004$. This is in agreement with values recently derived for young stars of solar composition and mass ∼3 M⊙. For μ1 Sco, we agree with previous authors that the secondary component is considerably oversized for its mass, implying binary (interactive) stellar evolution, probably of the ‘Case A’ type. The primary appears relatively little affected by this evolution, however. Its parameters show consistency with a star of its derived mass at age about 13 Myr, consistent with the star's membership of the Sco–Cen OB2 Association. The absolute parameters are as follows: M1 = 8.3 ± 1.0, M2 = 4.6 ± 1.0 (M⊙); R1 = 3.9 ± 0.3, R2 = 4.6 ± 0.4 (R⊙); T1 ∼ 24 000, T2 ∼ 17 000 (K); photometric distance ∼135 (pc).
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The mass-luminosity (M-L), mass-radius (M-R) and mass-effective temperature ($M-T_{eff}$) diagrams for a subset of galactic nearby main-sequence stars with masses and radii accurate to $\leq 3\%$ and luminosities accurate to $\leq 30\%$ (268 stars) has led to a putative discovery. Four distinct mass domains have been identified, which we have tentatively associated with low, intermediate, high, and very high mass main-sequence stars, but which nevertheless are clearly separated by three distinct break points at 1.05, 2.4, and 7$M_{\odot}$ within the mass range studied of $0.38-32M_{\odot}$. Further, a revised mass-luminosity relation (MLR) is found based on linear fits for each of the mass domains identified. The revised, mass-domain based MLRs, which are classical ($L \propto M^{\alpha}$), are shown to be preferable to a single linear, quadratic or cubic equation representing as an alternative MLR. Stellar radius evolution within the main-sequence for stars with $M>1M_{\odot}$ is clearly evident on the M-R diagram, but it is not the clear on the $M-T_{eff}$ diagram based on published temperatures. Effective temperatures can be calculated directly using the well-known Stephan-Boltzmann law by employing the accurately known values of M and R with the newly defined MLRs. With the calculated temperatures, stellar temperature evolution within the main-sequence for stars with $M>1M_{\odot}$ is clearly visible on the $M-T_{eff}$ diagram. Our study asserts that it is now possible to compute the effective temperature of a main-sequence star with an accuracy of $\sim 6\%$, as long as its observed radius error is adequately small (<1%) and its observed mass error is reasonably small (<6%).
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The most accurate stellar astrophysical parameters were collected from the solutions of the light and the radial velocity curves of 257 detached double-lined eclipsing binaries in the Milky Way. The catalogue contains masses, radii, surface gravities, effective temperatures, luminosities, projected rotational velocities of the component stars, and the orbital parameters. The number of stars with accurate parameters increased 67% in comparison to the most recent similar collection by Torres, Andersen, & Giménez (2010). Distributions of some basic parameters were investigated. The ranges of effective temperatures, masses, and radii are \$2\,750<T_{\text{eff}}\$(K) < 43000, 0.18 < M/M ⊙ < 33, and 0.2 < R/R ⊙ < 21.2, respectively. Being mostly located in one kpc in the Solar neighborhood, the present sample covers distances up to 4.6 kpc within the two local Galactic arms, Carina-Sagittarius and Orion Spur. The number of stars with both mass and radius measurements better than 1% uncertainty is 93, better than 3% uncertainty is 311, and better than 5% uncertainty is 388. It is estimated from the Roche lobe filling factors that 455 stars (88.5% of the sample) are spherical within 1% of uncertainty.
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The bright binary system YZ Cassiopeiae is a remarkable laboratory for studying the Am phenomenon. It consists of a metallic-lined A2 star and an F2 dwarf on a circular orbit, which undergo total and annular eclipses. We present an analysis of 15 published light curves and 42 new high-quality échelle spectra, resulting in measurements of the masses, radii, effective temperatures and photospheric chemical abundances of the two stars. The masses and radii are measured to 0.5 per cent precision: MA = 2.263 ± 0.012 M⊙, MB = 1.325 ± 0.007 M⊙, RA = 2.525 ± 0.011 R⊙ and RB = 1.331 ± 0.006 R⊙. We determine the abundance of 20 elements for the primary star, of which all except scandium are supersolar by up to 1 dex. The temperature of this star (9520 ± 120 K) makes it one of the hottest Am stars. We also measure the abundances of 25 elements for its companion (Teff = 6880 ± 240 K), finding all to be solar or slightly above solar. The photospheric abundances of the secondary star should be representative of the bulk composition of both stars. Theoretical stellar evolutionary models are unable to match these properties: the masses, radii and temperatures imply a half-solar chemical composition (Z = 0.009 ± 0.003) and an age of 490–550 Myr. YZ Cas therefore presents a challenge to stellar evolutionary theory.
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High-resolution spectroscopy of η Mus is combined with literature and new photometry to provide a comprehensive analysis of its components. Our main absolute parameters for the close binary system are M 1 and M 2 3.34 ± 0.04 M⊙, R 1 2.13 ± 0.07 R⊙, R 2 2.34 ± 0.10 R⊙; T 1 13 000 ± 300, T 2 12 600 ± 300, K; and distance 125 ± 10 pc. Our findings update earlier results in a number of respects. We thus confirm that η Mus B is a gravitationally bound companion of the close binary. This relates to the variable γ velocity of the radial velocities of η Mus A. We connect this to the recently discovered member η Mus D, whose orbit we link to new data. We also provide a spectroscopic examination of the Ap star η Mus B, listing over 450 identified lines. We argue that the system is still young, and the apparently anomalous rotation of the close binary’s secondary can be reconciled with its being a physically larger star, still condensing to the zero-age main sequence. Models of young condensing stars permit such expanded states, particularly during the deuterium-burning stage, and our results are in agreement with appropriate low-age models. This possible configuration may make η Mus an important example for testing young star models, formation, and evolution scenarios. This multiple star can be compared with V831 Cen and the general properties related to its membership of the Sco–Cen OB2 association.
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Physical dimensions and evolutionary status of the A-type twin binary GSC 4019 3345 are presented. Located at a distance of ~1.1 kpc from the Sun, the system was found to have two components with identical masses (M 1,2 = 1.92 M⊙), radii (R 1,2 = 1.76 R⊙), and luminosities (log L 1,2 = 1.1 L⊙) revolving in a circular orbit. Modeling the components with theoretical evolutionary tracks and isochrones implies a young age (t = 280 Myr) for the system, which is bigger than the synchronization time scale but smaller than the circularization time scale. Nevertheless, synthetic spectrum models revealed components’ rotation velocity of V rot12 = 70 km s−1, that is about three times higher than their synchronization velocity. No evidence is found for an age difference between the components.
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This paper presents results from analysing spectroscopic and multicolour photometric observations of the neglected semi-detached eclipsing binary system IO Ursae Majoris (IO UMa). For the first time, the orbital parameters of the system and fundamental physical properties of its components were determined from simultaneous analysis of BVR light curves and radial velocities of the components. The masses and radii of the primary and secondary components were found to be M1 = 2.11 ± 0.07 M⊙, M2 = 0.29 ± 0.02 M⊙ and R1 = 3.00 ± 0.04 R⊙ and R2 = 3.92 ± 0.05 R⊙, respectively. Derived absolute parameters yield the photometric distance of IO UMa as 263 ± 13 pc. The projected rotational velocity of the mass-accreting hotter component was measured as 34.5 ± 2 km s−1, just 1.28 times faster than the synchronous value. The hotter component of the system, located in the region of the instability strip, indicates pulsational variation with short period and small amplitude. Frequency analysis after subtracting the theoretical light curve from photometric data revealed that the more massive component shows δ Scuti type pulsation with four detected frequencies. The total amplitude of the variation in the V filter was found to be 0.03 mag. Mode identification using amplitude ratios and phase differences in different filters suggests that the main pulsation frequency of 22.0148 d−1 is probably a radial mode.
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Aims. We present the results of our detailed spectroscopic and photometric analysis of two previously unknown <1 M-circle dot detached eclipsing binaries: ASAS J045304-0700.4 and ASAS J082552-1622.8. Methods. With the HIgh Resolution Echelle Spectrometer (HIRES) on the Keck-I telescope, we obtained spectra of both objects covering large fractions of orbits of the systems. We also obtained V and I band photometry with the 1.0-m Elizabeth telescope of the South African Astronomical Observatory (SAAO). The orbital and physical parameters of the systems were derived with the PHOEBE and JKTEBOP codes. We investigated the evolutionary status of both binaries with several sets of widely-used isochrones. Results. Our modelling indicates that (1) ASAS J045304-0700.4 is an old, metal-poor, active system with component masses of M-1 = 0.8338 +/- 0.0036 M-circle dot, M-2 = 0.8280 +/- 0.0040 M-circle dot and radii of R-1 = 0.848 +/- 0.005 R-circle dot and R-2 = 0.833 +/- 0.005 R-circle dot, which places it at the end of the Main Sequence evolution - a stage rarely observed for this type of stars. (2) ASAS J082552-1622.8 is a metal-rich, active binary with component masses of M-1 = 0.7029 +/- 0.0045 M-circle dot, M-2 = 0.6872 +/- 0.0049 M-circle dot and radii of R-1 = 0.694(-0.011+0.007) R-circle dot and R-2 = 0.699(-0.014)(+0.011) R-circle dot. Both systems show significant out-of-eclipse variations, probably owing to large, cold spots. We also investigated the influence of a third light in the second system.
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We analyze extensive BVR_cI_c time-series photometry and radial-velocity measurements for WOCS 40007 (Auner 259; KIC 5113053), a double-lined detached eclipsing binary and a member of the open cluster NGC 6819. Utilizing photometric observations from the 1-meter telescope at Mount Laguna Observatory and spectra from the WIYN 3.5-meter telescope, we measure precise and accurate masses (~1.6% uncertainty) and radii (~0.5%) for the binary components. In addition, we discover a third star orbiting the binary with a period greater than 3000 days using radial velocities and Kepler eclipse timings. Because the stars in the eclipsing binary are near the cluster turnoff, they are evolving rapidly in size and are sensitive to age. With a metallicity of [Fe/H]=+0.09+/-0.03, we find the age of NGC 6819 to be about 2.4 Gyr from CMD isochrone fitting and 3.1+/-0.4 Gyr by analyzing the mass-radius (M-R) data for this binary. The M-R age is above previous determinations for this cluster, but consistent within 1 sigma uncertainties. When the M-R data for the primary star of the additional cluster binary WOCS 23009 is included, the weighted age estimate drops to 2.5+/-0.2 Gyr, with a systematic uncertainty of at least 0.2 Gyr. The age difference between our CMD and M-R findings may be the result of systematic error in the metallicity or helium abundance used in models, or due to slight radius inflation of one or both stars in the WOCS 40007 binary.
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We analyze extensive BVRCIC photometry and radial velocity measurements for three double-lined deeply eclipsing binary stars in the field of the old open cluster NGC?7142. The short period (P = 1.9096825 days) detached binary V375?Cep is a high probability cluster member, and has a total eclipse of the secondary star. The characteristics of the primary star (M = 1.288 ? 0.017 M ?) at the cluster turnoff indicate an age of 3.6?Gyr (with a random uncertainty of 0.25?Gyr), consistent with earlier analysis of the color-magnitude diagram. The secondary star (M = 0.871 ? 0.008 M ?) is not expected to have evolved significantly, but its radius is more than 10% larger than predicted by models. Because this binary system has a known age, it is useful for testing the idea that radius inflation can occur in short period binaries for stars with significant convective envelopes due to the inhibition of energy transport by magnetic fields. The brighter star in the binary also produces a precision estimate of the distance modulus, independent of reddening estimates: (m ? M)V = 12.86 ? 0.07. The other two eclipsing binary systems are not cluster members, although one of the systems (V2) could only be conclusively ruled out as a present or former member once the stellar characteristics were determined. That binary is within 05 of edge-on, is in a fairly long-period eccentric binary, and contains two almost indistinguishable stars. The other binary (V1) has a small but nonzero eccentricity (e = 0.038) in spite of having an orbital period under 5?days.
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Star clusters are superb astrophysical laboratories containing cospatial and coeval samples of stars with similar chemical composition. We have initiated the Sejong Open cluster Survey (SOS) - a project dedicated to providing homogeneous photometry of a large number of open clusters in the SAAO Johnson-Cousins' $UBVI$ system. To achieve our main goal, we have paid much attention to the observation of standard stars in order to reproduce the SAAO standard system. Many of our targets are relatively small, sparse clusters that escaped previous observations. As clusters are considered building blocks of the Galactic disk, their physical properties such as the initial mass function, the pattern of mass segregation, etc. give valuable information on the formation and evolution of the Galactic disk. The spatial distribution of young open clusters will be used to revise the local spiral arm structure of the Galaxy. In addition, the homogeneous data can also be used to test stellar evolutionary theory, especially concerning rare massive stars. In this paper we present the target selection criteria, the observational strategy for accurate photometry, and the adopted calibrations for data analysis such as color-color relations, zero-age main sequence relations, Sp - Mv relations, Sp - Teff relations, Sp - color relations, and Teff - BC relations. Finally we provide some data analysis such as the determination of the reddening law, the membership selection criteria, and distance determination.
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Spectrographic and photometric observations of three detached main sequence eclipsing binary systems with one or both components of type G, HS Aur, FL Lyr, and EW Ori, are analyzed. Ephemerides, V and R magnitudes, V-R indices, epochs, periods, e cos omega, photometric solutions, and spectrograms are presented for the systems. The radial velocities are analyzed and the orbital elements are obtained. A preliminary comparison of the systems is made with predictions from evolutionary models. HS Aur now represents a well-analyzed main sequence detached binary with both components having properties lying between those of the sun and the M1 dwarf YY Gem. In the case of FL Lyr, the two components differ significantly in their properties, making it of particular interest for its comparison with interior models and for its potential contribution to the flux and temperature scales.
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We report the detection of eclipses in GJ 3236, a bright (I = 11.6), very low mass binary system with an orbital period of 0.77 days. Analysis of light and radial velocity curves of the system yielded component masses of 0.38 ± 0.02 M ☉ and 0.28 ± 0.02 M ☉. The central values for the stellar radii are larger than the theoretical models predict for these masses, in agreement with the results for existing eclipsing binaries, although the present 5% observational uncertainties limit the significance of the larger radii to approximately 1σ. Degeneracies in the light curve models resulting from the unknown configuration of surface spots on the components of GJ 3236 currently dominate the uncertainties in the radii, and could be reduced by obtaining precise, multiband photometry covering the full orbital period. The system appears to be tidally synchronized and shows signs of high activity levels as expected for such a short orbital period, evidenced by strong Hα emission lines in the spectra of both components. These observations probe an important region of mass-radius parameter space around the predicted transition to fully convective stellar interiors, where there are a limited number of precise measurements available in the literature.
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Using a sample of 81 galactic, detached eclipsing binary stars we investigated the global zero-point shift of their parallaxes with the Gaia Data Release 2 (DR2) parallaxes. The stars in the sample lay in a distance range of 0.04-2 kpc from the Sun. The photometric parallaxes Phot of the eclipsing binaries were determined by applying a number of empirical surface brightness-color (SBC) relations calibrated on optical-infrared colors. For each SBC relation we calculated the individual differences and then we calculated unweighted and weighted means. As the sample covers the whole sky we interpret the weighted means as the global shifts of the Gaia DR2 parallaxes with respect to our eclipsing binary sample. Depending on the choice of the SBC relation the shifts vary from -0.094 to -0.025 mas. The weighted mean of the zero-point shift from all colors and calibrations used is d = -0.054 ± 0.024 mas. However, the SBC relations based on (B - K) and (V - K) colors, which are the least reddening dependent and have the lowest intrinsic dispersions, give a zero-point shift of d = -0.031 ± 0.011 mas in full agreement with results obtained by Lindegren et al. and Arenou et al. Our result confirms the global shift of Gaia DR2 parallaxes of d = -0.029 mas reported by the Gaia team, but we do not confirm the larger zero-point shift reported by a number of follow-up papers. © 2019. The American Astronomical Society. All rights reserved.
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Stellar parameters of the solar type twin binary V1719 Aql have been derived with relatively high accuracy. The erroneous known orbital period was corrected. The true period of the system (P=4.35 days) is twice the value known in the literature. The system is located at 77 ± 3 pc from the Sun, which matches, within the uncertainty box, the distance of 76 ± 1 pc given by the GAIA mission. The system consists of two G5V-type components with similar masses, radii and temperatures, respectively. The orbit is circular and the components rotate faster (25 kms−1) than their orbital synchronization velocity (10 kms−1). The number of G-type twins increases as predicted by the recent studies.
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Aims. The formation scenario of extended counter-rotating stellar disks in galaxies is still debated. In this paper, we study the S0 galaxy IC 719 known to host two large-scale counter-rotating stellar disks in order to investigate their formation mechanism. Methods. We exploit the large field of view and wavelength coverage of the Multi Unit Spectroscopic Explorer (MUSE) spectrograph to derive two-dimensional (2D) maps of the various properties of the counter-rotating stellar disks, such as age, metallicity, kinematics, spatial distribution, the kinematical and chemical properties of the ionized gas, and the dust map. Results. Due to the large wavelength range, and in particular to the presence of the Calcium Triplet λλ 8498, 8542, 8662 Å (CaT hereafter), the spectroscopic analysis allows us to separate the two stellar components in great detail. This permits precise measurement of both the velocity and velocity dispersion of the two components as well as their spatial distribution. We derived a 2D map of the age and metallicity of the two stellar components, as well as the star formation rate and gas-phase metallicity from the ionized gas emission maps. Conclusions. The main stellar disk of the galaxy is kinematically hotter, older, thicker and with larger scale-length than the secondary disk. There is no doubt that the latter is strongly linked to the ionized gas component: they have the same kinematics and similar vertical and radial spatial distribution. This result is in favor of a gas accretion scenario over a binary merger scenario to explain the origin of counter-rotation in IC 719. One source of gas that may have contributed to the accretion process is the cloud that surrounds IC 719.
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We use MARCS model atmosphere fluxes to compute synthetic colours, bolometric corrections and reddening coefficients for the Hipparcos/Tycho, Pan-STARRS1, SkyMapper and JWST systems. Tables and interpolation subroutines are provided to transform isochrones from the theoretical to various observational planes, to derive bolometric corrections, synthetic colours and colour-temperature relations at nearly any given point of the HR diagram for 2600 K < Teff < 8000 K, and different values of reddening in 85 photometric filters. We use absolute spectrophotometry from the CALSPEC library to show that bolometric fluxes can be recovered to ~2 percent from bolometric corrections in a single band, when input stellar parameters are well known for FG dwarfs at various metallicities. This sole source of uncertainty impacts interferometric effective temperatures to ~0.5 percent (or 30 K at the solar temperature). Uncertainties are halved when combining bolometric corrections in more bands, and limited by the fundamental uncertainty of the current absolute flux scale at 1 percent. Stars in the RAVE DR5 catalogue are used to validate the quality of our MARCS synthetic photometry in selected filters across the optical and infrared range. This investigation shows that extant MARCS synthetic fluxes are able to reproduce the main features observed in stellar populations across the Galactic disc.
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In connection with arranging IAU Symposium No. 50 on 'Spectral Classification and Multicolour Photometry', sponsored by Commissions 45 and 25, it was decided to exclude all calibration problems. Instead it was agreed that we should attempt to arrange a separate symposium, dealing with the fundamental problems of the cali­ bration of absolute magnitudes and temperatures of stars. The Executive Committee of the IAU accepted our proposal, and IAU Symposium No. 54 was held in Geneva on September 12-15, 1972, sponsored by thefollowing IAU Commissions: 24, 25, 29, 33, 35, 37,44 and 45. It was attended by about 90 scientists representing 16 countries. The Symposium was divided into eight sessions. Each session started with a review paper by an invited speaker; this was followed by a general discussion including a few contributed papers. The contents of the present volume follow closely the programmes of the individual sessions of the Symposium. Most of the recorded discussions have been kept, and only in a few cases have the order of questions and comments been altered so as to obtain more homogeneity in the presentation.
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We present fits to the broadband photometric spectral energy distributions (SEDs) of 158 eclipsing binaries (EBs) in the Tycho-2 catalog. These EBs were selected because they have highly precise stellar radii, effective temperatures, and in many cases metallicities previously determined in the literature, and thus have bolometric luminosities that are typically good to $\lesssim$ 10%. In most cases the available broadband photometry spans a wavelength range 0.4-10 $\mu$m, and in many cases spans 0.15-22 $\mu$m. The resulting SED fits, which have only extinction as a free parameter, provide a virtually model-independent measure of the bolometric flux at Earth. The SED fits are satisfactory for 156 of the EBs, for which we achieve typical precisions in the bolometric flux of $\approx$ 3%. Combined with the accurately known bolometric luminosity, the result for each EB is a predicted parallax that is typically precise to $\lesssim$ 5%. These predicted parallaxes---with typical uncertainties of 200 $\mu$as---are 4-5 times more precise than those determined by Hipparcos for 99 of the EBs in our sample, with which we find excellent agreement. There is no evidence among this sample for significant systematics in the Hipparcos parallaxes of the sort that notoriously afflicted the Pleiades measurement. The EBs are distributed over the entire sky, span more than 10 mag in brightness, reach distances of more than 5 kpc, and in many cases our predicted parallaxes should also be more precise than those expected from the Gaia first data release. The EBs studied here can thus serve as empirical, independent benchmarks for these upcoming fundamental parallax measurements.
Chapter
In chapter 1 basic methods are reviewed, and applications and suggestions for future work are presented. In chapter 2 a revision is given of the intrinsic-colour relation in the U, B, V system of hot main-sequence stars. Some temperature-colour relations are discussed in chapter 3, where also a correction formula is given for the effects of interstellar reddening on the effective temperatures of hot main-sequence stars. An empirical mass-luminosity relation is given in chapter 4.
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We present spectroscopic and photometric study of V421 Peg. This eclipsing binary displays lines from both components that are well separated. This allowed us to classify the primary and secondary component as F(1 ± 0.5) V and F(2 ± 0.5) V, respectively. We use our radial velocity measurements together with Hipparcos and ASAS photometry and apply simultaneous analysis, which yields masses and radii of the primary and secondary components as M1 = 1.594 ± 0.029 M⊙, M2 = 1.356 ± 0.029 M⊙ and R1 = 1.584 ± 0.028 R⊙, R2 = 1.328 ± 0.029 R⊙, respectively. Positions of the components in HR diagram suggest that the primary component is a γ Doradus variable candidate. Spectroscopic and photometric properties of the system indicates reddening value of = 0m.021 which puts the system to the distance of 158 ± 4 pc.
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The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the "Cygnus X" complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this $\ell\simeq80$ degree sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus~X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg~OB2. We find distances of $1.33\pm0.17$, $1.32\pm0.07$, $1.44\pm0.18$, and $1.32\pm0.13$ kpc toward MT91~372, MT91~696, CPR2002~A36, and Schulte~3 respectively. We adopt a weighted average distance of 1.33$\pm$0.06~kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg~OB2. We also identify Schulte 3C (O9.5V), a 4" visual companion to the 4.75 day binary Schulte~3(A+B), as a previously unrecognized Association member.
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Astrometric surveys such as Gaia and LSST will measure parallaxes for hundreds of millions of stars. Yet they will not measure a single distance. Rather, a distance must be estimated from a parallax. In this didactic article, I show that doing this is not trivial once the fractional parallax error is larger than about 20%, which will be the case for about 80% of stars in the Gaia catalogue. Estimating distances is an inference problem in which the use of prior assumptions is unavoidable. I investigate the properties and performance of various priors and examine their implications. A supposed uninformative uniform prior in distance is shown to give very poor distance estimates (large bias and variance). Any prior with a sharp cut-off at some distance has similar problems. The choice of prior depends on the information one has available - and is willing to use - concerning, for example, the survey and the Galaxy. I demonstrate that a simple prior which decreases asymptotically to zero at infinite distance has good performance, accommodates non-positive parallaxes, and does not require a bias correction.
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We present VRI light curves and spectra in the wavelength range 8110–9140 Å of the binary CoRoT 102932176. From the comparison of the spectra of CoRoT 102932176 with standard stars we classify the primary component of the binary as a type F0V star, while the secondary seems to be a late type K4V star. From the fit of the VRI light curves we derive the absolute stellar parameters: M 1 = 1.58 ±± 0.15 M⊙, T eff,1 = 7300 ±± 50 K, R 1 = 1.63 ±± 0.05 R⊙, M 2 = 0.64 ±± 0.06 M⊙, T eff,2 = 4547 ±± 80 K, R 2 = 0.73 ±± 0.02 R⊙. The solutions show that CoRoT 102932176 is a detached system, with main-sequence components, an age log t (yr) ≃≃ 8.90 and located at about 760 pc from Earth.
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AP And is a well-detached F5 eclipsing binary star for which only a very limited amount of information was available before this publication. We have obtained very extensive measurements of the light curve (19097 differential V magnitude observations) and a radial velocity curve (83 spectroscopic observations) which allow us to fit orbits and determine the absolute properties of the components very accurately: masses of 1.277 +/- 0.004 and 1.251 +/- 0.004 solar masses, radii of 1.233 +/- 0.006 and 1.1953 +/- 0.005 solar radii, and temperatures of 6565 +/- 150 K and 6495 +/- 150 K. The distance to the system is about 400 +/- 30 pc. Comparison with the theoretical properties of the stellar evolutionary models of the Yonsei-Yale series of Yi et al. shows good agreement between the observations and the theory at an age of about 500 Myr and a slightly sub-solar metallicity.
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Time-related binary system characteristics such as orbital period, its rate of change, apsidal motion, and variable light-time delay due to a third body, are measured in two ways that can be mutually complementary. The older way is via eclipse timings, while ephemerides by simultaneous whole light and velocity curve analysis have appeared recently. Each has its advantages, for example, eclipse timings typically cover relatively long time spans while whole curves often have densely packed data within specific intervals and allow access to systemic properties that carry additional timing information. Synthesis of the two information sources can be realized in a one step process that combines several data types, with automated weighting based on their standard deviations. Simultaneous light-velocity-timing solutions treat parameters of apsidal motion and the light-time effect coherently with those of period and period change, allow the phenomena to interact iteratively, and produce parameter standard errors based on the quantity and precision of the curves and timings. The logic and mathematics of the unification algorithm are given, including computation of theoretical conjunction times as needed for generation of eclipse timing residuals. Automated determination of eclipse type, recovery from inaccurate starting ephemerides, and automated data weighting are also covered. Computational examples are given for three timing-related cases—steady period change (XY Bootis), apsidal motion (V526 Sagittarii), and the light-time effect due to a binary's reflex motion in a triple system (AR Aurigae). Solutions for all combinations of radial velocity, light curve, and eclipse timing input show consistent results, with a few minor exceptions.
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We present results from analysis of combined spectroscopic and photometric data for three eclipsing binary systems: AP And, VZ Cep and V881 Per. Based on new, multicolour photometric light curves and spectroscopically determined mass ratio values, we derived accurate physical parameters of the components. Two of the systems, namely VZ Cep and V881 Per, were found to be magnetically active. The variability of V881 Per was studied in several sets of data [Northern Sky Variability Survey (NSVS), Wide Angle Search for Planets (WASP) and newly derived] gathered at different epochs. We show that the huge differences in the shape of its light curve can be explained by just a single model differing only in number of spots and their location on the surface of the primary component.
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Multicolor photometric and polarimetric observations of the eclipsing binary EK Cep at the Crimean Astrophysical Observatory in 1995 and 2006–2007 are reported. Polarimetric observations were made of stars in the neighborhood of EK Cep. It is shown that the observed linear polarization of EK Cep is determined by a variable circumstellar constituent, as well as by the interstellar component. Various possible mechanisms for formation of the intrinsic polarization of binary stars are discussed.
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We present measurements of dust reddening using the colors of stars with spectra in the Sloan Digital Sky Survey. We measure reddening as the difference between the measured and predicted colors of a star, as derived from stellar parameters from the Sloan Extension for Galactic Understanding and Exploration Stellar Parameter Pipeline. We achieve uncertainties of 56, 34, 25, and 29 mmag in the colors u - g, g - r, r - i, and i - z, per star, though the uncertainty varies depending on the stellar type and the magnitude of the star. The spectrum-based reddening measurements confirm our earlier "blue tip" reddening measurements, finding reddening coefficients different by -3%, 1%, 1%, and 2% in u - g, g - r, r - i, and i - z from those found by the blue tip method, after removing a 4% normalization difference. These results prefer an RV = 3.1 Fitzpatrick reddening law to O'Donnell or Cardelli et al. reddening laws. We provide a table of conversion coefficients from the Schlegel et al. (SFD) maps of E(B - V) to extinction in 88 bandpasses for four values of RV , using this reddening law and the 14% recalibration of SFD first reported by Schlafly et al. and confirmed in this work.
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Accurate masses and radii have been determined from new spectroscopic and photometric observations and from previously published photometric observations and times of minima of this pair of F5 V stars. Previous reports of δ Scuti variations by the components appear to be erroneous. IT Cas has an eccentric orbit, but existing observations cover too small a fraction of the apsidal motion variations to fit an accurate apsidal period, which is estimated to be 2200 years based on theoretical models. These models give an age near 2 billion years for the binary star. There is a small amount of color excess due to interstellar reddening.
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Period distributions have been examined for various spectral types of about 600 (eclipsing and spectroscopic) close binaries, which are likely to be substantially unevolved. The comparison with the previous corresponding analyses of extensive (but heterogeneous) binary samples allows a clarification of the extent of the evolutionary and observational selection effects. Remarkably, this analysis reveals a great deficiency of short period binaries (with periods corresponding to case A mass transfer) in the whole spectral range. For the late spectral types, this result may be connected with postformation angular momentum loss caused by stellar wind magnetic braking; at least for the late B and A spectral range, a ready interpretation of this finding is that close binaries of corresponding periods and spectral types are rarely formed.
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This paper provides improved numerical relations between effective temperatures of stars, their B - V colors, and their bolometric corrections (B Cs) for the purpose of comparing theoretical stellar evolutionary calculations to color-magnitude diagrams of star clusters. Temperatures and bolometric correction measurements for 335 stars from the literature form the observational basis for the transformations. Measured temperatures range from 2900 to 52,500 K. Polynomial fits to the observations give relations between effective temperatures and B - V colors and between temperatures and bolometric corrections. Hot supergiants appear to have a Teff:B-V relation slightly different from those of main-sequence stars, subgiants, and giants. All luminosity classes appear to follow a unique Teff:BC relation. The Teff:BC relation for stars with temperatures less than ˜5000 K, however, is uncertain because temperatures of the coolest stars are determined from uncertain angular diameters.
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Spectrographic orbits of these three double-lined binaries are determined from spectrograms obtained at the Lick Observatory. The photometric observations of ZZ Boo by McNamara et al. and of CW Eri by Chen are reanalyzed, and revised properties of the components are derived. The properties of the most definitive F-type stars are shown in the mass-radius, mass-luminosity, and color-magnitude planes, along with zero-age relations. The components of the three systems analyzed here are among the more evolved binaries having both components in the state of core hydrogen burning.
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Eclipsing binaries can improve multiple system statistics via the light-time effect and radial velocity shifts. Here an algorithm operates on data of mixed type to exploit these opportunities. Main reasons for enhanced reliability are that (1) combined light and velocity curves give better timewise coverage than either type alone, (2) properly weighted solutions impersonally balance light and velocity information, and (3) the entire theory is within the computer model, so observations are used directly without corrections. A brief history of mixed whole-curve solutions is given and the relative importance of light-time and radial velocity input for third-body parameters is discussed and quantified. Period sifting by power spectral analysis is essentially indispensable in preliminary work. Applications are to the Algol-type system DM Persei and the detached system VV Orionis. An assumption of coplanarity for DM Per's inner and outer orbits is tested and quantified by dynamical experiments. Derived third-body parameters for DM Per are mainly reasonable and self-consistent. For comparison with whole-curve results, we also investigated DM Per's ephemeris in terms of eclipse timings and found whole-curve solutions to give smaller standard errors in reference epoch (T0), binary orbit period (P), and dP/dt, over a similar baseline in time. An astonishing outcome is lack of evidence that can pass reasonable validity tests for VV Ori's well-accepted third star with P ≈ 120 days. Estimates of third light do indicate a third star, but the correct period cannot now be established, so the star cannot be identified as the one heretofore recognized from radial velocity evidence. The much cited 120 day period appears to be an artifact of the window function for VV Ori's historical velocity observations.