Reconsidering The Bailey Diagrams of ab-type RR Lyrae Stars, Metallicity-Mediated Evolution as the Direct Cause of the Oosterhoff Phenomenon

L. -J. Li, S. -B. Qian, L. -Y. Zhu +2

We re-examine the Bailey diagrams of fundamental mode RR Lyrae stars from the perspective of horizontal branch (HB) evolution, identifying evolutionary effects as the probable dire…