FZ Orionis: a short period W UMa system

PhotoelectricU , B andV observations of the eclipsing binary system FZ Orionis obtained by the author during three years 1984, 1985 and 1986 are presented and studied. The present photometry may settle the dispute regarding the class and the period of the system light variation between the GCVS 1969 ( Lyr;p = 1.597 d) and Figer (1983) and Le Brogneet al. (1984) (W UMa;p 0.4 d) in favour of the latter. A period change was detected which may be elucidated as due to the presence of a third body and mass exchange between the components. Times of ten minima were determined and new ephemeris have been deduced. The present light and colour curves were investigated and preliminary parameters for the system could be estimated.