COMMUNICATIONS / MITTEILUNGEN
Period Changes of RR Lyrae Stars I.
AT And, SU Dra, RR Leo, TT Lyn and AR Per
No. 71
Budapest, 1978
Abstract
Photographic and photoelectric observations obtained at Konkoly Observatory
during the past 45 years are presented. Using all available observations the
O-C diagrams of AT And, SU Dra, RR Leo, TT Lyn and AR Per are constructed.
Period jumps are characteristic of AT And and TT Lyn. In the period of AT And
two jumps occured: +710 x 10-8 days in 1956 and -545 x 10-5 days in 1962.
The period of TT Lyn is constant, but a jump of 8 x 10-5 days might have
been taken place in 1958. The O-C diagram of SU Dra consists of waves of
small amplitude, the photoelectric maxima from 1955 were able to to be fitted
by a straight line. The period of AR Per shows a constant increase with time
at rate of 1.01 x 10-8 days/year. The period of RR Leo also shows increase
at a rate of 15.849 x 10-8 days/year during the past 70 years. A more
rigorous period analysis showed that cyclic variations with an amplitude of
0.006-0.007 days and with cycle length of 25000 epoch numbers were
superimposed on the positive parabolic O-C diagram.
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