SPOT cycles in the RS CVn variable AY Cet.
Abstract
New UBV photometry of AY Cet from 1981-82, 1982-83, and 1983-84 is presented and analyzed along with previously collected data. Various period-finding and curve-fitting techniques are used to describe the progressive damping of the sine wave and the progressive brightening of the mean luminosity. The model is developed of a group of starspots concentrated on one hemisphere and whose area gradually gets smaller. The V data between 1980 and 1984 are represented as a combination of three sine curves. The 77-day period produces a variation whose full amplitude in V decreases from 0.22 mag in 1980-81 to 0.12 mag in 1983-84, while the mean V magnitude brightens gradually by about 0.12 mag. B-V and U-B remain constant over the rotation period of the G5 III spectroscopy primary, but, as the mean brightness increases, B-V becomes more negative while U-B becomes more positive. An orbital period of 57.1 d is determined, and AY Cet is confirmed as the second example of clearly asynchronous rotation in an RS CVn binary.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 1986
- Bibcode:
- 1986A&A...157....1P
- Keywords:
-
- Binary Stars;
- Periodic Variations;
- Starspots;
- Stellar Spectrophotometry;
- Ubv Spectra;
- Variable Stars;
- Light Curve;
- Orbital Elements;
- Radial Velocity;
- Spectral Energy Distribution;
- Spectrum Analysis;
- Stellar Luminosity;
- White Dwarf Stars;
- Astrophysics