SIMBAD references

The binary system HD193576 = V444 Cyg was observed in 1999-2006 to obtain radial velocities of its components - O-type star and WR-type star. From the measured data of the NV 4604 emission line the orbital period P=4.212450±0.000048 days was found. This result confirms the rate of the period change given by Underhill et al. (1990). Using the radial velocity curves of the NV 4604 emission line and the HI 4861 absorption line we found the following masses and orbital elements for the system: M_O=28.4±0.6 M_☉, M_ WR_=12.4±0.5 M_☉, a_O=11.5±0.3 R_☉, a_ WR_=26.2±0.3 R_☉, γ_O=-26±2 km/s, γ_ WR_=45±1 km/s, K_O=136±3 km/s and K_ WR_=309±2 km/s. Using our estimates for the orbital period and masses, and the rate of period change given by Underhill et al. (1990), we got the mass-loss rate of the WR component {dot}(M=4.6)x10^–6 M_☉/yr. We confirm that radial velocity values obtained by the bisector method are of sufficient accuracy to be used in analysis of the mass-loss and wind-wind collision processes in V444 Cyg.