Rapid oscillations in cataclysmic variables. IV. WZ Sagittae.
Abstract
An extensive study of the rapid coherent oscillations in the light curve of the dwarf nova WZ Sagittae is presented. Data in 1978 show conclusively that the 27.87 s oscillation is a clock of high stability, maintaining a constant period and a nearly constant phase for many months. A period increase of 1 part in 100,000 occurred between 1977 and 1978, and all oscillation timings during 1976-1978 can be fitted with a linearly increasing period. Random 'phase jitter' of 30 deg is also found in the timings, superposed on the strictly periodic process. The mean power spectrum shows weak signals at frequencies slightly lower than the fundamental frequency. A model is presented in which the oscillation is attributed to the rotation of an accreting, magnetized white dwarf. Most of the observed phenomena can be understood in this model, but the large period increase in the recent data remains a problem. Difficulties and predictions of the model are discussed.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1980
- DOI:
- 10.1086/158336
- Bibcode:
- 1980ApJ...241..235P
- Keywords:
-
- Eclipsing Binary Stars;
- Light Curve;
- Novae;
- Stellar Oscillations;
- Stellar Rotation;
- White Dwarf Stars;
- Power Spectra;
- Stellar Luminosity;
- Stellar Mass Accretion;
- Stellar Models;
- Astrophysics;
- Cataclysmic Variables:Models;
- Dwarf Novae:Oscillations;
- Dwarf Novae:Period Changes;
- Dwarf Novae:White Dwarfs;
- Rotation:White Dwarfs