[en] Oscillating Algol-type eclipsing binaries (oEA) are very interesting objects that have three observational features of eclipse, pulsation, and mass transfer. Direct measurement of their masses and radii from the double-lined radial velocity data and photometric light curves would be the most essential for understanding their evolutionary process and for performing the asteroseismological study. We present the physical properties of the oEA star XX Cep from high-resolution time-series spectroscopic data. The effective temperature of the primary star was determined to be 7946 ± 240 K by comparing the observed spectra and the Kurucz models. We detected the absorption lines of the secondary star, which had never been detected in previous studies, and obtained the radial velocities for both components. With the published BVRI light curves, we determined the absolute parameters for the binary via Wilson–Devinney modeling. The masses and radii are $M_1=2.49\pm <!--\; ??\; -->0.06M_{\odot <!--\; ???\; -->}$, $M_2=0.38\pm <!--\; ??\; -->0.01M_{\odot <!--\; ???\; -->}$, $R_1=2.27\pm <!--\; ??\; -->0.02R_{\odot <!--\; ???\; -->}$, and $R_2=2.43\pm <!--\; ??\; -->0.02R_{\odot <!--\; ???\; -->}$, respectively. The primary star is about $45\mathrm{\%<!--\; \%\; -->}$ more massive and $60\mathrm{\%<!--\; \%\; -->}$ larger than the zero-age main sequence stars with the same effective temperature. It is probably because XX Cep has experienced a very different evolutionary process due to mass transfer, contrasting with the normal main sequence stars. The primary star is located inside the theoretical instability strip of δ Sct-type stars on the HR diagram. We demonstrated that XX Cep is an oEA star, consisting of a δ Sct-type pulsating primary component and an evolved secondary companion.

[en] We present new elements of apsidal motion in three eccentric eclipsing binaries located in the Large Magellanic Cloud. The apsidal motions of the systems were analyzed using both light curves and eclipse timings. The OGLE-III data obtained during the long period of 8 yr (2002-2009) allowed us to determine the apsidal motion period from their analyses. The existence of third light in all selected systems was investigated by light curve analysis. The O – C diagrams of EROS 1018, EROS 1041, and EROS 1054 were analyzed using the 30, 44, and 26 new times of minimum light, respectively, determined from full light curves constructed from EROS, MACHO, OGLE-II, OGLE-III, and our own observations. This enabled a detailed study of the apsidal motion in these systems for the first time. All of the systems have a significant apsidal motion below 100 yr. In particular, EROS 1018 shows a very fast apsidal period of 19.9 ± 2.2 yr in a detached system.

[en] NSVS 02502726 has been known as a double-lined, detached eclipsing binary that consists of two low-mass stars. We obtained BVRI photometric follow-up observations in 2009 and 2011 to measure improved physical properties of the binary star. Each set of light curves, including the 2008 data given by Çakirli et al., was simultaneously analyzed with the previously published radial velocity curves using the Wilson-Devinney binary code. The conspicuous seasonal light variations of the system are satisfactorily modeled by a two-spot model with one starspot on each component and by changes of the spot parameters with time. Based on 23 eclipse timings calculated from the synthetic model and one ephemeris epoch, an orbital period study of NSVS 02502726 reveals that the period has experienced a continuous decrease of –5.9 × 10^–7 day yr^–1 or a sinusoidal variation with a period and semi-amplitude of 2.51 yr and 0.0011 days, respectively. The timing variations could be interpreted as either the light-travel-time effect due to the presence of an unseen third body, or as the combination of this effect and angular momentum loss via magnetic stellar wind braking. Individual masses and radii of both components are determined to be M₁ = 0.689 ± 0.016 M_☉, M₂ = 0.341 ± 0.009 M_☉, R₁ = 0.707 ± 0.007 R_☉, and R₂ = 0.657 ± 0.008 R_☉. The results are very different from those of Çakirli et al. with the primary's radius (0.674 ± 0.006 R_☉) smaller the secondary's (0.763 ± 0.007 R_☉). We compared the physical parameters presented in this paper with current low-mass stellar models and found that the measured values of the primary star are best fitted to a 79 Myr isochrone. The primary is in good agreement with the empirical mass-radius relation from low-mass binaries, but the secondary is oversized by about 85%.

[en] Multiband CCD photometric observations of SZ Her were obtained between 2008 February and May. The light curve was completely covered and indicated a significant temperature difference between both components. The light-curve synthesis presented in this paper indicates that the eclipsing binary is a classical Algol-type system with parameters of q = 0.472, i = 87.⁰57, and Δ(T₁ - T₂) = 2381 K; the primary component fills approximately 77% of its limiting lobe and is slightly larger than the lobe-filling secondary component. More than 1100 times of minimum light spanning more than a century were used to study an orbital behavior of the binary system. It was found that the orbital period of SZ Her varied due to a combination of two periodic variations with cycle lengths of P₃ = 85.8 yr and P₄ = 42.5 yr and semi-amplitudes of K₃ = 0.013 days and K₄ = 0.007 days, respectively. The most reasonable explanation for these variations is a pair of light-time effects driven by the possible existence of two M-type companions with minimum masses of M₃ = 0.22 M_☉ and M₄ = 0.19 M_☉ that are located close to the 2:1 mean motion resonance. If two additional bodies exist, then the overall dynamics of the multiple system may provide a significant clue to the formation and evolution of the eclipsing pair.

[en] New multiband CCD photometry is presented for V407 Peg; the R _C light curves are the first ever compiled. Our light curves, displaying a flat bottom at secondary minimum and an O'Connell effect, were simultaneously analyzed with the radial velocity (RV) curves given by Rucinski et al. The light changes of the system are best modeled using both a hot spot on the secondary star and a third light. The model also represents historical light curves. All available minimum epochs, including our six timing measurements, have been examined and they indicate that the eclipse timing variation is mainly caused by light asymmetries due to the spot activity detected in the light-curve synthesis. The hot spot may be produced as a result of the impact of the gas stream from the primary star. Our light and velocity solutions indicate that V407 Peg is a totally eclipsing A-type overcontact binary with values of q = 0.251, i = 87.°6, ΔT = 496 K, f = 61%, and l ₃ = 11∼16%. Individual masses and radii of both components are determined to be M ₁ = 1.72 M _☉, M ₂ = 0.43 M _☉, R ₁ = 2.15 R _☉, and R ₂ = 1.21 R _☉. These results are very different from previous ones, which is probably caused by the light curves with distorted and inclined eclipses used in those other analyses. The fact that there are no objects optically related to the system and that the seasonal RVs show a large discrepancy in systemic velocity indicates that the third light source most likely arises from a tertiary component orbiting the eclipsing pair.

[en] We present the physical properties of V404 Lyr exhibiting eclipse timing variations and multiperiodic pulsations from all historical data including the Kepler and SuperWASP observations. Detailed analyses of 2922 minimum epochs showed that the orbital period has varied through a combination of an upward-opening parabola and two sinusoidal variations, with periods of P ₃ = 649 days and P ₄ = 2154 days and semi-amplitudes of K ₃ = 193 s and K ₄ = 49 s, respectively. The secular period increase at a rate of +1.41 × 10^–7 days yr^–1 could be interpreted as a combination of the secondary to primary mass transfer and angular momentum loss. The most reasonable explanation for both sinusoids is a pair of light-travel-time effects due to two circumbinary objects with projected masses of M ₃ = 0.47 M _☉ and M ₄ = 0.047 M _☉. The third-body parameters are consistent with those calculated using the Wilson-Devinney binary code. For the orbital inclinations i ₄ ≳ 43°, the fourth component has a mass within the hydrogen-burning limit of ∼0.07 M _☉, which implies that it is a brown dwarf. A satisfactory model for the Kepler light curves was obtained by applying a cool spot to the secondary component. The results demonstrate that the close eclipsing pair is in a semi-detached, but near-contact, configuration; the primary fills approximately 93% of its limiting lobe and is larger than the lobe-filling secondary. Multiple frequency analyses were applied to the light residuals after subtracting the synthetic eclipsing curve from the Kepler data. This revealed that the primary component of V404 Lyr is a γ Dor type pulsating star, exhibiting seven pulsation frequencies in the range of 1.85-2.11 day^–1 with amplitudes of 1.38-5.72 mmag and pulsation constants of 0.24-0.27 days. The seven frequencies were clearly identified as high-order low-degree gravity-mode oscillations which might be excited through tidal interaction. Only eight eclipsing binaries have been known to contain γ Dor pulsating components and, therefore, V404 Lyr will be an important test bed for investigating these rare and interesting objects.

[en] We present new photometric data of the transiting planet HAT-P-12b observed in 2011. Our three transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law. Including our measurements, 18 transit times spanning about 4.2 yr were used to determine the improved ephemeris with a transit epoch of 2,454,187.85560 ± 0.00011 BJD and an orbital period of 3.21305961 ± 0.00000035 days. The physical properties of the star-planet system are computed using empirical calibrations from eclipsing binary stars and stellar evolutionary models, combined with both our transit parameters and previously known spectroscopic results. We found that the absolute dimensions of the host star are M_A = 0.73 ± 0.02 M_☉, R_A = 0.70 ± 0.01 R_☉, log g_A = 4.61 ± 0.02, ρ_A = 2.10 ± 0.09 ρ_☉, and L_A = 0.21 ± 0.01 L_☉. The planetary companion has M_b = 0.21 ± 0.01 M_Jup, R_b = 0.94 ± 0.01 R_Jup, log g_b = 2.77 ± 0.02, ρ_b = 0.24 ± 0.01 ρ_Jup, and T_eq = 960 ± 14 K. Our results agree well with standard models of irradiated gas giants with a core mass of 11.3 M_⊕.

[en] We present the periods of apsidal motion for 27 early-type eclipsing binaries with high eccentricity located in the Small Magellanic Cloud. New times of minima were derived from the light curves constructed by the MACHO, Optical Gravitational Lensing Experiment (OGLE)-II, and OGLE-III survey data. The eclipse timing diagrams of the binary systems were analyzed using those timings and the elements of apsidal motions were obtained in detail for the first time. The apsidal motion periods of all systems were estimated by detailed analysis of both eclipse timings and light curves; a strong correlation value between both methods is shown. We confirm that OGLE-SMC-ECL-2194 shows the shortest known apsidal motion period of 7.1 yr in a detached system with main sequence stars. Nineteen systems show intermediate apsidal motion periods between 10 and 100 yr, and seven systems exhibit long apsidal periods of more than 100 yr

[en] We present the physical properties of the semi-detached Algol-type eclipsing binary Y Cam based on high resolution spectra obtained using the Bohyunsan Optical Echelle Spectrograph. This is the first spectroscopic monitoring data obtained for this interesting binary system, which has a δ Sct-type pulsating component. We obtained a total of 59 spectra over 14 nights from 2009 December to 2011 March. Double-lined spectral features from the hot primary and cool secondary components were well identified. We determined the effective temperatures of the two stars to be T_e_f_f_,_1 = 8000 ± 250 K and T_e_f_f_,_2 = 4629 ± 150 K. The projected rotational velocities are v_1sin i_1 = 51 ± 4 km s"−"1 and v_2sin i_2 = 50 ± 10 km s"−"1, which are very similar to a synchronous rotation with the orbital motion. Physical parameters of each component were derived by analyzing our radial velocity data together with previous photometric light curves from the literature. The masses and radii are M_1 = 2.08 ± 0.09 M_⊙, M_2 = 0.48 ± 0.03 M_⊙, R_1 = 3.14 ± 0.05 R_⊙, and R_2 = 3.33 ± 0.05 R_⊙, respectively. A comparison of these parameters with the theoretical evolution tracks showed that the primary component is located between the zero-age main sequence and the terminal-age main sequence, while the low-mass secondary is noticeably evolved. This indicates that the two components have experienced mass exchange with each other and the primary has undergone an evolution process different from that of single δ Sct-type pulsators

[en] We present new multiband CCD photometry for WZ Cyg made on 22 nights in two observing seasons of 2007 and 2008. Our light-curve synthesis indicates that the system is in poor thermal contact with a fill-out factor of 4.8% and a temperature difference of 1447 K. Including our 40 timing measurements, a total of 371 times of minimum light spanning more than 112 yr were used for a period study. Detailed analysis of the O-C diagram showed that the orbital period has varied by a combination of an upward parabola and a sinusoid. The upward parabola means continuous period increase and indicates that some stellar masses are thermally transferred to the more massive primary star at a rate of about 5.80 x 10^-8 M_sun yr^-1. The sinusoidal variation with a period of 47.9 yr and a semi-amplitude of 0.008 days can most likely be interpreted as the light-travel-time effect due to the existence of a low-mass M-type tertiary companion with a projected mass of M₃sin i₃ = 0.26 M_sun. We examined the evolutionary status of WZ Cyg from the absolute dimensions of the eclipsing pair. It belongs to the marginal contact binary systems before the broken contact phase, consisting of a massive primary star with spectral type F4 and a secondary star with type K1.