V444 Cyg BV differential light curves

The Wilson-Devinney (WD) analysis, using new BV observations carried out at the Ankara University Observatory, revealed the masses, radii, and temperatures of the components of the system as M_WR_=10.64M_{sun}_, M_O_=24.68M_{sun}_, R_WR_=7.19R_{sun}_, R_O_=6.85R_{sun}_, T_WR_=31000K, and T_O_=40000K, respectively. It was found that both components had a full spherical geometry, whereas the circumstellar envelope of the WR component had an asymmetric structure.

The O-C analysis of the system revealed a period lengthening of 0.139+/-0.018s/yr, implying a mass loss rate of (6.76+/-0.39)x10^-6^M_{sun}/yr for the WR component. Moreover, 106 IUE-NEWSIPS spectra were obtained from NASA's IUE archive for line identification and determination of line profile variability with phase, wind velocities and variability in continuum fluxes. The integrated continuum flux level (between 1200-2000{AA}) showed a mild and regular increase from orbital phase 0.00 up to 0.50 and then a decrease in the same way back to phase 0.00.