New UBV photoelectric observational data on 42 northern Cepheids with periods of 5-10 days are presented. The period changes and the variations in the light curve of the observed Cepheids are investigated. No secular light curve variation has been discovered. The O-C diagrams of CV Mon and RS Ori show a period jump and a subsequent rejump to the earlier value of the period. These two Cepheids as well as the shorter period ones with a rejumping period are probably members of binary systems. Another effect can be pointed out in AW Per and DD Cas which are also members of binary systems: the apparent period changes due to the orbital motion around the common centre of gravity can be seen. Both the orbital period and the value of a x sin i can be determined for these latter two stars. The combined effect (i.e.. the effect of the orbital motion and the rejumping period) can be seen in the O-C diagram of the short period Cepheid SU Cygni.
Commmunications of the Konkoly Observatory Hungary
- Pub Date:
- January 1980