SIMBAD references

The blue spectra of the components of Y Cygni are analysed by means of NLTE model photospheres. The disentangling technique is used for the reconstruction of the individual spectra of the components of this well detached binary. This method makes it possible to determine the photospheric parameters of the binary components by means of spectral analysis with the same accuracy as for single stars. We obtained the following parameters for the primary/secondary: T_eff=34500/34200±600, logg_eff=4.16/4.18±0.10, helium abundance by number fraction ε_He=0.08/0.08±0.01, v_rsini=142/138±2km/s and the light ratio l=0.928±0.011. The temperatures are significantly higher than those found in photometric studies. From their position in the logg-logT_effdiagram and comparison with theoretical evolutionary tracks we conclude that both components of the system are very close to the zero age main sequence. The spectroscopic orbit is redetermined with improved accuracy. The orbit eccentricity is found to be e=0.142±0.002 in agreement with results from light curve analysis. We determined radial velocity amplitudes of 238.9±0.5km/s and 246.4±0.5km/s corresponding to a mass ratio of q=0.970±0.005. The best fit to the blue photometry of [MK59] yields the inclination i=86.37deg±0.12deg and the relative radii. Combination of these values with the spectroscopic orbit allows the determination of absolute dimensions: M₁=17.57±0.27M_☉, M₂=17.04±0.26M_☉, and the polar radii R_p,1=5.93±0.07R_☉, R_p,2=5.78±0.07R_☉. The evolutionary age of Y Cygni as found by comparison of temperatures and gravities with evolutionary tracks is bracketed by the time scales for synchronization and circularization predicted by tidal theory.