On the Difference Between the Oosterhoff Types i and II Globular Clusters
Abstract
The period-frequency distribution of RR Lyrae variables in a globular cluster is interpreted in terms of pulsation theory. The globular cluste?s M3 and Cen are the most populous representatives of Oosterhoff types I and II, respectively. By studying their period-frequency distributions in detail we conclude that the variables in c Cen are either more massive by A log = 0.10 or more helium rich by A V = 0.20 than the variables in M3. Reasons are given for preferring the former alternative. It is shown that this difference is a general property of the Oosterhoff types I and II. If this mass difference is correct, then we conclude that differential mass loss must occur in the two types of clusters between the main sequence and the horixontal branch in the sense that the metal-rich clusters lose more mass than the metal-weak clusters.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1971
- DOI:
- 10.1086/151094
- Bibcode:
- 1971ApJ...168..381S