A photometric study of the massive binary RY Sct

The present study deals with the problem of the estimation of the orbital a nd physical parameters for the EB-type eclipsing binary RY Sct, based on th e interpretation of new photometric U B V R observations. The light curves obtained at the Maidanak Observatory during 1979-94 show a slight asymmetry around the secondary minima and a small difference in the height of the su ccessive maxima. The light curves are analysed in the framework of the Roch e computer model (Djurasevic 1992a) by applying the inverse-problem method (Djurasevic 1992b) based on Marquardt's (1963) algorithm. The analysis show s that RY Sct system is in an overcontact configuration (f(over) similar to 33%) with q = m(2)/m(1) = 3.3 and i similar to 84.degrees3, generating tot al-annular eclipses. The basic parameters of the system and of the active r egion are estimated for all individual U, B, V and R light curves. Our resu lts suggested a mass exchange between the components and mass loss through the outer Lagrangian point L-3. This could be taken as a possible mechanism in the formation of the circumstellar envelope of toroidal form lying in t he orbital plane of the system.