The reddening of type AB RR Lyrae stars

The paper modifies Sturch's (1966) method for deriving, from observed near-minimum light colors, EB-V values for RR Lyrae stars with Bailey's types for a or b light curves in order to avoid the use of reddening and metallicity-sensitive U-B colors. The Delta(S), (Fe/H) calibration is examined, and blanketing corrections are derived from synthetic colors of models by Kurucz (1975, 1979). Sturch's finding that the intrinsic blanketing-corrected near-minimum light B-V color of a variable can be estimated from its period is verified. The inherent accuracy of the method is discussed and found to depend appreciably on cycle-to-cycle color variations. Comparisons are made with other reddening determinations. The blanketing corrections determined by Sturch from delta(U-B) values are found to make his EB-V values less than those found in the present study, while his estimated intrinsic colors make his EB-V values greater than those found in this study.