Period Changes in Dwarf Cepheids, II. YZ Bootis, XX Cygni and DY Herculis
Abstract
The period changes in the dwarf cepheids YZ Boo, XX Cyg and DY Her are discussed and O-C diagrams of these stars are constructed. The period of XX Cyg changed abruptly in 1942 (deltaP= +87 x 10E-9 day = +0.0075 sec). Besides the sudden increase of the period, it has also shown small fluctuations. With regard to YZ Boo there may be a slight continuous increase (at a rate Beta = + 10.6 x 10E-13 day cycleE-1 = + 3.2 x 10E-2 sec centuryE-1) in its period. The period of DY Her has shown a definite continuous decrease at a rate Beta = -37.2 x 10E-13 day cycleE-1 = -7.9 x 10E-2 sec centuryE-1 during the time interval covered by photoelectric observations (1951-1979).
- Publication:
-
Commmunications of the Konkoly Observatory Hungary
- Pub Date:
- January 1981
- Bibcode:
- 1981CoKon..75....1S