L. Szabados

Northern Cepheids: Period Update and Duplicity Effects

No. 96 (Vol. 11, Part 3)
Budapest, 1991


O-C diagrams have been continued for 64 northern Cepheids with the primary aim of studying the effects of duplicity on the pulsation period. Because the light-time effect in the O-C diagrams of binary Cepheids has to be accompanied with properly phased variations in the gamma-velocity, the radial velocity of the programme stars has been studied, as well. Light-time effect is suspected in the O-C diagram of FM Aql, RW Cam, Y Lac and RS Ori, and confirmed for AW Per. One or more phase jumps are present or suspected in the O-C diagram of 19 northern Cepheids (FF Aql, BY Cas, DD Cas, DL Cas, X Cyg, SU Cyg, SZ Cyg, DT Cyg, V532 Cyg, V924 Cyg, TX Del, DX Gem, X Lac, CV Mon, RS Ori, SV Per, SZ Tau, T Vul, X Vul). In addition to the Cepheids with known spectroscopic orbit, the spectroscopic binary nature based on the variability of the gamma-velocity has been confirmed, revealed or suspected for the majority of the programme stars. The most probable new spectroscopic binary Cepheids are: KL Aql, Eta Aql, SU Cas, V636 Cas, BZ Cyg, MW Cyg, V386 Cyg, W Gem, RZ Gem, AD Gem, RS Ori, SV Per, SW Tau, T Vul and U Vul. A preliminary value of the orbital period is suggested for Eta Aql, SU Cas, RZ Gem, T Vul and U Vul.

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