RR Lyrae Variable Pulsations and the Oosterhoff Groups

摘要

It is concluded that Oosterhoff group I clusters have 0.55 M/sub sun/ stars and group II clusters have 0.65 M/sub sun/ stars. The Y value is always about 0.29. Mean log L/L/sub sun/ values are 1.66 and 1.78 giving M/sub bol/ = 0.60 and 0.30 for the RR Lyrae variables in these two groups of clusters. For field RR Lyrae variables at M = approx. 0.5 M/sub sun/ or less, perhaps M/sub bol/ = 0.90 or even larger as Clube and Jones propose. Apparently all evolution is blueward for RR Lyrae variables, and the color overlap of F and 1H pulsators is not real.