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In this study, we have explored the frequency separations, Δ ν and δ ν 02 , the height and width of the oscillation power excess, H Gauss and δ ν env , as a function of the frequency of maximum power ν max by analyzing 187 evolved stars in six star clusters observed by the Kepler / K2 missions. We have also examined the asteroseismic relation in the Christensen-Dalsgaard diagram. Given the importance of scaling relations, the dependency of asteroseismic scaling relations on physical quantities must be verified to reduce systematic errors through the exploration of observational data obtained from various sources. In this context, the star cluster provides a valuable means to assess the age and metallicity. Focusing on evolved stars with 30 μ Hz < ν max < 220 μ Hz , we have exploited the mass effect without the need for deriving the individual stellar mass. We have found that the considered relations appear to be associated with the age of star clusters, thereby the mass of the stars in a given evolutionary status for star clusters with different ages. By separately considering red giant branch stars and red clump stars, we have found that red clump stars appear more sensitive to the cluster age compared with red giant branch stars. It has been suggested that conclusions regarding the dependency of metallicity should be drawn with due care as outcomes are subject to how to treat metallicity. Finally, we conclude by briefly pointing out implications of our findings on asteroseismic inferences. • We analyze asteroseismic data of evolved stars in the six Kepler/K2 star clusters. • Asteroseismic relations depend on stellar mass, reflecting the cluster age. • Metallicity should be carefully handled, comparing isochrone fit with spectroscopy. • Red clump stars are more sensitive to cluster age than red giant branch stars. [ABSTRACT FROM AUTHOR]

The accuracy of absolute parameters' estimation in contact binary systems is important for investigating their evolution and solving some challenges. The Gaia DR3 parallax is one of the methods used for estimating the absolute parameters, in cases where photometric data is the only one that is available. The use of this method includes advantages and limitations that we have described and examined in this study. We selected 48 contact binary systems whose mass ratios were mostly obtained by spectroscopic data, in addition to a number of photometric studies. The target systems were suitable for A V and the Re-normalized Unit Weight Error (RUWE), and their absolute parameters were calculated based on Gaia DR3 parallax, observational information, orbital period, and light cure solution from the literature and catalogs. The outcomes of OO Aql differed significantly from those reported in the literature. Upon analyzing the system's light curve with TESS data, we concluded that the stars' temperatures were the reason for this difference, and utilizing Gaia DR3 parallax provided reasonable results. We displayed the target systems on the Hertzsprung–Russell (HR), q − L r a t i o , P − M V , and l o g M t o t − l o g J 0 diagrams, and the systems are in good agreement with the theoretical fits. We showed that the estimation of absolute parameters with this method might be acceptable if Δ a (R ⊙) is less than ∼ 0. 1 (R ⊙). There are open questions regarding the existence of l 3 in the light curve analysis and its effect on the estimation of absolute parameters with this method. • We discussed using Gaia DR3 parallax to estimate absolute parameters. • We performed light curve analysis for OO Aql using TESS data. • Parameters such as A V , V , and T have an important effect on the acceptable results. [ABSTRACT FROM AUTHOR]

• OT UMa and UG Leo undergo partial eclipses. • They are of W subtype with middle fillout factors. • Their global parameters are determined based on GAIA distances. • The components of the two targets have similar characteristics. We present photometric observations of the W UMa binaries OT UMa and UG Leo. Our results from the light curve solutions are: (i) The two targets show partial eclipses; (ii) The components OT UMa and UG Leo are of G spectral type; (iii) Detailed q -search analysis was carried out for determination of the mass ratios; (iv) The two binaries are of W subtype with middle fillout factors. We estimated masses, radii and luminosities of the target components by our light curve solutions and using GAIA distances. It turned out that their values are similar for the two targets. The paper presents a discussion on the determination of the temperatures and mass ratios of partially-eclipsing W UMa stars. [ABSTRACT FROM AUTHOR]

Highlights • The orbital period distribution of contact binaries shows gab for their short periods. • New detection of binary stars enlarges the data base necessary to follow their evolution. • Analyzing data using modern software gives accurate orbital and physical parameters. • Determining the binary parameters will give the opportunity to verify theories. • Classifying contact binaries to A- and W-types enable to follow their evolution. Abstract In a previous paper, we have presented photometric studies of four recently discovered contact binaries (Djurašević, et al., 2016; hereafter Paper I) that were observed by the 1.88 m telescope of the Kottamia Astronomical Observatory (KAO) in Egypt. In this paper we continue studying two more recently discovered, by some of us, contact binaries UCAC4 479-113658 and UCAC4 479-113711, and analyze their light curves to determine orbital and physical parameters using the modeling program of G. Djurašević as in Paper I. The analysis shows that the two systems are W UMa contact binaries of late type main-sequence stars with a bright spot on the secondary less massive cool star of the first system; and spot on each component of the later system. We also conclude that both systems are most likely to be of the A-type class. [ABSTRACT FROM AUTHOR]

Photometric observations in V, R c and I c bands of the ultrashort-period W UMa binaries 1SWASP J044132.96+440613.7, 1SWASP J052926.88+461147.5 and NSVS 2175434 are presented. The results from the modeling and analysis of our observations reveal that: (i) All targets undergo total eclipses and their photometric mass ratios should be accepted with confidence; (ii) All stellar components are late-type dwarfs; (iii) The temperature difference of target components does not exceed 150 K; (iv) All targets have overcontact configurations with fill-out factor around 0.24; (v) The orbit of NSVS 2175434 is slightly eccentric which is unusual for such an ultrashort-period binary; (vi) The orbital periods of all targets were improved. Masses, radii and luminosities of the stellar components were estimated by the empirical relation “period, orbital axis” for short- and ultrashort-period binaries. [ABSTRACT FROM AUTHOR]

Photometric observations in Sloan g ′ and i ′ bands of the W UMa binaries V0951 Per, CSS J062803.2+571604, CSS J222157.2+275308, CSS J075135.6+382028, V0338 Dra, NSVS 2256852, NSVS 4666412, V1355 Tau, NSVS 4808227, NSVS 4726498, CSS J075350.1+264830 and HL Lyn are presented. The light curve solutions revealed that these binaries have overcontact configurations with small fillout factors (within 0.1–0.2). Seven of them undergo total eclipses and their photometric mass ratios should be accepted with confidence. The temperature differences of the components of CSS J062803.2+571604 and NSVS 2256852 exceed 1100 K which is unusual for overcontact binaries. We suspect that NSVS 2256852 is a probable candidate for merger due to its small mass ratio of q = 0.16 and to the registered decreasing of the orbital period. [ABSTRACT FROM AUTHOR]

We present the first comprehensive catalog of the γ Doradus type pulsating stars. This catalog covers observational properties of all γ Dor variables obtained until January 2017. The photometric and physical properties of 109 w e l l − k n o w n γ Dor pulsators, 18 hybrid stars, 13 anomalous γ Dor stars, and 22 γ Dor stars in eclipsing plus 1 non–eclipsing SB2 binary systems are presented as separate tables. In addition, 291 candidate γ Dor variables discovered by CoRot , 307 candidate γ Dor, 205 hybrid and 11 candidate γ Dor in binaries discovered by Kepler were also presented. Distribution of the genuine single γ Dor pulsators in the P puls -T eff , Amplitude -T eff , Amplitude -P puls and L-T eff diagrams are presented and discussed. We find following correlations for the γ Dor pulsators in the eclipsing binaries: P puls ∝ P orb 0.27 , P puls ∝ Q 0.45 , and P puls ∝ r − 0.44 , where ( Q ) is the pulsation constant and r is the fractional radius of the pulsating component in the binary system. The correlation coefficients are not high enough due to limited sample and scattering in the data. [ABSTRACT FROM AUTHOR]

We present the first light curve analysis of the eclipsing binary V658 Lyr. B, V and I c photometric observations made from 2014 to 2017 of this W UMa-type binary star are collected, the complete light curves were obtained in 2015 (4 nights) and 2016 (11 nights) and are used for a detailed photometric analysis to determine orbital and physical parameters using the Wilson-Devinney code. The results obtained indicates that V658 Lyr is an A-type overcontact binary system with both components of spectral type (G2 + G4). Based on our 17 ToM the short orbital period of the eclipsing binary was confirmed and revised to P = 0.3302577 days. The orbital period was found to show a cyclic variations and a decrease rate of dP/dt = − 2.97 × 10 − 7 days yr − 1 , which can be interpreted as a mass transfer from the more massive component to the less massive one. We have not found an asymmetry of the light curves. The mass of the primary and secondary stars are calculated to be M 1 = 1.18M ⊙ ( ± 0.08) and M 2 = 0.21M ⊙ ( ± 0.01) indicating the primary to be underluminous for its mass and the secondary to be overluminous for its mass. [ABSTRACT FROM AUTHOR]

We present the results of our investigation of the geometrical parameters of the W UMa-type binary system VSX J045718.3+405643 (short name VSX J0457) based on new CCD B, V and I c light curves. Our observations were carried out during six nights in November and December 2016 using the 0.25 m telescope of the Stazione Astronomica Betelgeuse in Magnago, Northern Italy. Six new times of minima and light elements have been determined and the observed light curves were analysed using the Wilson–Devinney code. The output model reveals that the system is a contact binary of A-Subtype of the W Ursae Majoris systems with a mass ratio of q  ∼  0.26 and a degree of contact factor f  ∼  32%. The primary component is hotter than the secondary by 95 K, this suggests us that the system is under thermal contact. The high orbital inclination ( i = 82°.2) implies that VSX J0457 is a total eclipsing binary system and the photometric parameters here obtained are quite reliable. The absolute physical parameters of the two components in VSX J0457 are estimated. Based on these estimated parameters the evolutionary state of the system components is investigated and discussed. Combining our photometric solution with the 3-D correlation obtained for contact binaries by Gazeas (2009) we derive the masses and radii of the components of this eclipsing system as M 1 = 1.44M ⊙ , M 2 = 0.38M ⊙ , R 1 = 1.55R ⊙ and R 2 = 0.87R ⊙ . The distance to VSX J0457 was calculated as 147 pc from this analysis, taking into account interstellar extinction. [ABSTRACT FROM AUTHOR]

We present first ground-based multi-colors photometric study of an eccentric, double-lined eclipsing binary system V402 Lac. Analyzing the data obtained in this study together with earlier studies in the literature we derived the orbital and physical parameters of this detached binary system of considerable interest. Derived physical parameters of the components are as follows; M 1 = 2.95 ± 0.06 M ⊙ , M 2 = 2.86 ± 0.06 M ⊙ , R 1 = 2.61 ± 0.04 R ⊙ , R 2 = 2.16 ± 0.03 R ⊙ , L 1 = 98 ± 5 L ⊙ and L 2 = 69 ± 3 L ⊙ . Using the newly obtained parameters the distance of the binary is determined to be 262 ± 33 pc. In addition, the system show apsidal motion whose period is determined to be 213 years. A possible third star ( M 3 sin i = 1.9 M ⊙ ) orbiting the binary system in an eccentric orbit ( e = 0.23 ) with an orbital period of 20.5 years has been detected in this study with LTT. [ABSTRACT FROM AUTHOR]

The VRI light curves were measured for the low-mass eclipsing binary V608 Cam as a part of our long-term observational project for studying of eclipsing binaries with a short orbital period. The Tess light curve solution in Phoebe results to the detached configuration, where the temperature of the primary component was fixed to T 1 = 5300 K according to Gaia results, which gives us T 2 = 4110 ± 50 K for the secondary. The spectral type of the primary component was derived to be K0 and the photometric mass ratio was estimated q = 0. 92 ± 0. 07. Characteristics and temporal variation of the dark region on the surface of the secondary component were estimated and are attributed to apparent period changes of this eclipsing binary with a cycle of about 2.4 yr. • The VRI light curves were measured for the eclipsing binary V608 Cam. • The TESS light curve solution in Phoebe results to the detached configuration with the photometric mass ratio 0.92(0.07). • The asymmetric light curve and the difference in brightness in maxima are probably the result of a dark region on the secondary. • Its characteristics and temporal variation were estimated and are attributed to apparent period changes with a cycle of about 2.4 yr. [ABSTRACT FROM AUTHOR]

KIC 9851142 (V2094 Cyg, HD 188854) is an eccentric eclipsing binary with an orbital period of P orb = 8.4854 d, exhibiting millimagnitude (mmag) amplitude pulsations on time scales of a few days. I present the results of the analysis of high-resolution spectroscopic data and Kepler long and short cadence photometry. The iterative combination of spectral classification by atmospheric analysis, radial velocity and eclipse timing variation studies, separation of pulsational features of the light curve, and binary light curve analysis led to the accurate determination of the fundamental stellar parameters and the comparison with evolutionary models strict constraints on the system age. I found that the binary is composed of two main sequence stars with an age of 0.75 ± 0.21 Gyr, having masses, radii and temperatures of M 1 = 1.79 ± 0.11 M ⊙ , R 1 = 2.47 ± 0.07 R ⊙ , T eff1 = 7250 ± 480 K for the primary, and M 2 = 0.83 ± 0.12 M ⊙ , R 2 = 0.67 ± 0.05 R ⊙ , T eff2 = 5050 ± 650 K for the secondary. Multiple frequency analyses techniques were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of KIC 9851142 is a γ Dor type pulsating star, exhibiting five pulsation frequencies in the range of 0.6–1.95 d −1 with amplitudes of 0.29–6.72 mmag and pulsation constants of 0.24–0.27 d. The analysis of the eclipse timing variations revealed preliminary apsidal motion with a period of P apse obs = 240 ± 29 y. Only six eclipsing binaries have been known to contain γ Dor pulsating components and, therefore, KIC 9851142 will be an important test-bed for examining these exceptional and interesting objects. [ABSTRACT FROM AUTHOR]

We present long term ground-based photometric variations of the Algol type binary system SZ Her. Modeling of the system shows that the secondary component is filling Roche lobe. The parameters for the primary and the secondary components have been determined as M 1 = 1.56 ± 0.05 M ⊙ , M 2 = 0.77 ± 0.03 M ⊙ , R 1 = 1.61 ± 0.10 R ⊙ , R 2 = 1.55 ± 0.09 R ⊙ , L 1 = 6.5 ± 0.5 L ⊙ , L 2 = 1.1 ± 0.1 L ⊙ while the separation of the components is a = 4.9 ± 0.3 R ⊙ . Newly obtained parameters yield the distance of the system as 302 ± 12 pc. We collected all the photometric and CCD times of mid-eclipse available in the literature and combined them with the newly obtained eight times of light minima. Analysis of the mid-eclipse times indicate a period increase of dP dt = + 3.1 ( 2 ) × 10 - 8 days/yr that can be interpreted in terms of the mass transfer rate as dM dt = + 2.62 ( 3 ) × 10 - 9 M ⊙ / yr from the secondary to the primary component. The orbital period of the system oscillates with periods of 118 years and 30 years with corresponding semi-amplitudes of 0.0057 days and 0.0055 days, respectively. These changes were analyzed under the assumption of the existence of third and fourth bodies in the system. [ABSTRACT FROM AUTHOR]

• We determined the fundamental parameters of 83 B-type stars from NOAO Indo-U.S. Library. • Barbier-Chalonge-Divan (BCD) method and line blanketed LTE/NLTE model atmospheres are used. • Comparison with earlier studies is performed. • Approximate masses of the target stars are determined. In this article, we present a spectroscopic analysis of 83 field B-type stars from NOAO Indo-U.S. Library. We calculated the fundamental parameters such as effective temperatures, surface gravities, and rotational velocities using Barbier-Chalonge-Divan (BCD) method and line blanketed LTE/NLTE model atmospheres. The projected rotational velocities were estimated by fitting the Mg II4481 Å line profile with theoretical lines calculated from LTE/NLTE models. The evolutionary masses for the program stars are estimated using the evolutionary models. In most of the cases, the present study gives fair agreement with earlier investigations and is even more accurate in some cases. [ABSTRACT FROM AUTHOR]

Abstract: A detailed spectroscopic study of a Cephei variable star, Ceti, is presented. Physical fundamental parameters are estimated from the best fitting of 26 neutral helium lines and Balmer profiles: effective temperature, superficial gravity and projected rotation velocity. Non-LTE abundances of He, C, N, O, Ne, Mg, Al, Si, P, S, Ar and Fe are achieved using model atmospheres with updated atomic data. Our analysis show an N-enrichment and Fe overabundance, with [O/Fe] −0.73dex, confirming this object to be a metal-rich star, which is a requirement for the -mechanism to trigger the pulsations observed in Cephei stars. [Copyright &y& Elsevier]

Abstract: In this work the results of a spectroscopic study of the southern field narrow-line Be star HD 171054 are presented. High dispersion and signal-to-noise ratio spectra allowed the estimation of the fundamental photospheric parameters such as the projected rotational velocity, effective temperature and superficial gravity from non-LTE stellar atmosphere models. From these parameters and microturbulence, the abundances of He, C, N, O, Mg, Al and Si for this object are estimated. Results show that C is depleted whereas N is overabundant compared with the sun and OB stars in the solar vicinity. Oxygen and helium are close to the solar value. Magnesium is down by 0.43dex and aluminium and silicon are overabundant. [Copyright &y& Elsevier]

Abstract: Ten eclipsing binaries, identified in the scope of the CoRoT Space Mission, were selected for analysis. The photometric light curves were processed and analyzed, resulting in the first study of eclipsing binary candidates with their possible photometric solution, in the context of the above-mentioned Space Mission. The selected targets are detached and overcontact systems, for which we computed 2MASS temperatures, in addition to different physical parameters, including orbital period, orbit inclination angle, and temperatures, radius and luminosity ratios. This study reveals a large diversity of eclipsing binary systems obtained from the CoRoT data. [ABSTRACT FROM AUTHOR]