UBV Photometry of the Massive Eclipsing Binary TT Aur

UBV observations carried out mainly at the Turkish National Observatory (TUG) and the collected times of eclipse minima of the massive eclipsing binary TT Aur were used to study the system parameters. The simultaneous solution of the light curves by Wilson-Devinney (1992) code yields a semi-detached configuration with slightly larger Roche-lobe filling secondary. The shoulders of primary minimum indicate some excess absorption probably due to circumstellar material in the form of partial disk around the primary component. The deeper primary minimum in U filter can be an indication of a hotter region on the facing hemisphere of the primary. The period variation of the system reveals the existence of a possible third component star in a circular orbit around the system.