COMMUNICATIONS / MITTEILUNGEN

B. Szeidl , K. Oláh and A. Mizser

Period Changes of RR Lyrae Stars II, TW Her, VZ Her, AV Peg and TU UMa

No. 89 (Vol. 10, Part 3)
Budapest, 1986

Abstract

Photographic and photoelectric observations obtained at Konkoly Observatory during the past 35 years are presented. Using all available observations the O-C diagrams of TW Her, VZ Her, AV Peg and TU UMa are constructed. The period of TW Her is constant whereas that of VZ Her, AV Peg and TU UMa is changing. The periods of VZ Her and AV Peg show an increase at a rate of +1.144x10^-10 day/cycle = 8.20 ms/year and +1.846x10^-10 day/cycle = 14.92 ms/year, respectively whereas the period of TU UMa is decreasing at a rate of -0.210x10^-10 day/cycle = -4.02 ms/year. Superimposed on the parabolic O-C diagrams of AV Peg and TU UMa are cyclic variations which may result from the duplicity of these stars.

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