The period shortening of RY Sagitarii.
Abstract
Using 10,000 visual estimates taken from the literature and obtained between 1897 and 1977, the 39-day period, 0.6-mag amplitude cycle of RY Sgr is analyzed. 2800 averages were made with these estimates and 460 dates of maxima and an equal number of minima were determined. A secular period change is found analyzing these dates. In the time interval studied the period change is from 39.4 to 38.2 days. Superimposed on this variation is a sinusoidal phase change suggesting a periodicity of about half a century. On top of these two phenomena there are phase shifts of about 10 days that happen rather randomly. These phase shifts seem to be associated with the deep minima of this R CrB-type variable. The meaning of the secular period change is discussed and alternatively explained as mass loss or rapid evolution changes. A possible explanation of the random phase shifts is given.
- Publication:
-
The Astronomical Journal
- Pub Date:
- December 1982
- DOI:
- 10.1086/113266
- Bibcode:
- 1982AJ.....87.1775M
- Keywords:
-
- Light Curve;
- Periodic Variations;
- Secular Variations;
- Stellar Spectrophotometry;
- Variable Stars;
- Data Reduction;
- Electrophotometry;
- R Coronae Borealis Stars;
- Stellar Evolution;
- Astronomy