Researches on the Variations in the Period of the Binary R Cma

The eclipsing binary R CMa was observed by means of the photoelectric photometric method in February, 1981. A moment when the primary minimum appeared has been measured. Comparing the moments when the primary minima reached, collected by other authors, with ours, we consider that the variations in the period of R CMa are the light-time orbital effect caused by the third body that moves around the binary. After calculating, we obtain the mass function of the third body f(m)=(m₃³sin³i')/(m₁₂+m₃)²=0.024M⊙.