Period changes in DF hydrae

Abstract

The period study of the eclipsing binary DF Hya, based on up-to-date minima has been presented. The least-squares method has been applied to obtain a new period, which comes out to be .ᵈ3306017. Period changes are found around the years 1949, 1974 and 1982. Appreciable period changes are apparent around 1949 and 1974, the strongest being around 1974. the period changes (ΔP) range from 0.46 × 10−⁶ d to 0.46 10−⁵ d, the average being 1.89 × 10−⁶d. such period changes are usual for a contact system, like DF Hya. Our results do not show increase in the time interval 1959-1985 as suggested by Zhang et al. (1989).