Hello! Just looking over my curves for DY HER and SZ HYA. B-V seems to narrow at minimum compared to maximum for these two stars.
Is this a common feature of SPVs? Thank you and best regards.
I believe most…
I believe most pulsators (certainly Cepheids, RRLs, HADS) have a larger amplitudes in bluer colours than in redder colours so yes this would be common.
Sorry, this is a late reply. Sturch found that all ab-type RR Lyrae stars have similar B-V colors at minimum light. RRab stars, you may recall, are those pulsating in the fundamental radial mode. Observed B-V colors at minimum for RRab stars can therefore be used to measure their amount of interstellar reddening. RRab stars do not all have the same color at maximum. RRc stars, RR Lyrae stars which pulsate in the first overtone mode, show more variability in color at minimum, and are in general bluer than RRab stars. Thus, there is some difference in behavior for different types of SSP, although the general rule may hold.