Double-lined eclipsing binaries allow accurate and direct determination of fundamental parameters such as mass and radius for each component, and they provide important constraints on the stellar structure and evolution models. In this study, we aim to determine a unique set of binary parameters for the Algol system W UMi and to examine its evolutionary status. New high-resolution time-series spectroscopic observations were carried out during 14 nights from April 2008 to March 2011, and a total of 37 spectra were obtained using the Bohyunsan Optical Echelle Spectrograph. We measured the radial velocities (RVs) for both components, and the effective temperature of the primary star was found to be T eff,1 = 9310 ± 90 K by a comparison of the observed spectra and the Kurucz models. The physical parameters of W UMi were derived by an analysis of our RV data together with the multi-band light curves of Devinney et al. (1970). The individual masses, radii, and luminosities of both components are M 1 = 3.68 ± 0.10 M ⊙ and M 2 = 1.47 ± 0.04 M ⊙ , R 1 = 3.88 ± 0.03 R ⊙ and R 2 = 3.13 ± 0.03 R ⊙ , and L 1 = 102 ± 1 L ⊙ and L 2 = 7.3 ± 0.1 L ⊙ , respectively. A comparison of these parameters with theoretical stellar models showed that the primary component lies in the main-sequence band, while the less massive secondary is noticeably evolved.The results indicate that the initially more massive star became the present secondary by losing most of its own mass via mass transfer to the companion (present primary).

OO Dra is a short-period Algol system with a δ Sct-like pulsator. We obtained timeseries spectra between 2016 February and May to derive the fundamental parameters of the binary star and to study its evolutionary scenario. The radial velocity (RV) curves for both components were presented, and the effective temperature of the hotter and more massive primary was determined to be T eff,1 = 8260 ± 210 K by comparing the disentangling spectrum and the Kurucz models. Our RV measurements were solved with the BV light curves of Zhang et al. (2014) using the Wilson-Devinney binary code. The absolute dimensions of each component are determined as follows:Comparison with stellar evolution models indicated that the primary star resides inside the δ Sct instability strip on the main sequence, while the cool secondary component is noticeably overluminous and oversized. We demonstrated that OO Dra is an oscillating post-mass transfer R CMa-type binary; the originally more massive star became the low-mass secondary component through mass loss caused by stellar wind and mass transfer, and the gainer became the pulsating primary as the result of mass accretion. The R CMa stars, such as OO Dra, are thought to have formed by non-conservative binary evolution and ultimately to evolve into EL CVn stars.

We present the first high-resolution spectra for the eclipsing binary V404 Lyr showing γ Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of T eff,1 = 7, 330 ± 150 K and a rotational velocity of v 1 sini = 148 ± 18 km s −1 . The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted Kepler data gives us accurate stellar and system parameters of V404 Lyr. The masses, radii, and luminosities are M 1 = 2.17±0.06 M ⊙ , R 1 = 1.91±0.02 R ⊙ , and L 1 = 9.4±0.8 L ⊙ for the primary, and M 2 = 1.42±0.04 M ⊙ , R 2 = 1.79±0.02 R ⊙ , and L 2 = 2.9±0.2 L ⊙ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of M 3b = 0.71±0.15 M ⊙ in an orbit of P 3b = 642±3 days, e 3b = 0.21±0.04, and a 3b = 509±2 R ⊙ . The third light of l 3 = 4.1 ± 0.2% could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipsesubtracted light residuals, we detected 45 frequencies with signal to noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies (f 1 − f 6 , f 9 ), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a γ Dor-type variable star.