Eclipsing Binary System WN3(h)+O5V BAT99-129: Analysis of the MACHO Light Curve and the Parameters of the Components

BAT99-129 is a massive eclipsing binary system in the Large Magellanic Cloud (LMC) which consists of WN3(h) and O5V components. A broad-band MACHO light curve of the system is studied in the present paper. A dense and extended atmosphere of the Wolf-Rayet (WR) star does not allow one to analyze the light curve in terms of standard parametric models of Wilson-Devinney type. Distributions of brightness and absorption across the WR star disk are restored using direct solution of integral equations describing eclipses in the system. As a result, reliable estimates of the orbital inclination and component parameters have been obtained. The orbital inclination is 78 deg, the orbital separation is 28.5 solar radii, the radius of the O component is 7.1 solar radii. The size of the WR component core opaque in optical continuum is 3.4 solar radii. The brightness temperature in the center of the WR disk is about 45000K. Probable errors of the parameters are discussed. Evolutionary status of the system is discussed.