On the photometric metallicity of Oosterhoff-type I and II RRab stars

Abstract

We are revising the consistency of photometric metallicity formulae widely used for fundamental-mode RR Lyrae (RRab) variables, based on their V- and I-band light curves, published by Jurcsik and Kovács (1996) and Smolec (2005), respectively. 293 RRab variables belonging to 10 globular clusters, all simultaneously containing stars of both Oosterhoff types, are selected for this purpose. We find that on average, the V-band formula results in higher estimated metallicities by about 0.05 dex than the I-band formula. Moreover, we detect a dependency on the Oosterhoff class of the variables for both formulae, as well. Using the V-band formula, Oo I stars are 0.05-0.10 dex more metal rich than Oo II stars of the same cluster. Although with less significance, but the I-band results indicate a reversed trend. Therefore, we surmise that the average difference we have found between the V- and I-band formulae is the consequence of the total sample being dominated by Oo I variables.

10 pages, 7 figures, accepted for publication in MNRAS

References in corpus (11)

• Iron and neutron-capture element abundance variations in the globular cluster M2 (NGC 7089)
• Discovery of $\sim$ 9,000 new RR Lyrae in the Southern Catalina Surveys
• Evidence for Distinct Components of the Galactic Stellar Halo from 838 RR Lyrae Stars Discovered in the LONEOS-I Survey
• The halo+cluster system of the Galactic globular cluster NGC1851
• Models of the Mass-Ejection Histories of pre Planetary Nebulae, IV. Magnetized Winds and the Origins of Jets, Bullets, and FLIERs
• Revisiting the variable star population in NGC~6229 and the structure of the Horizontal Branch
• A Census of Variability in Globular Cluster M68 (NGC 4590)
• Light and Heavy Element Abundance Variations in the Outer Halo Globular Cluster NGC 6229
• On the Oosterhoff dichotomy in the Galactic bulge: I. spatial distribution
• A Detailed Study of Giants and Horizontal Branch Stars in M68: Atmospheric Parameters and Chemical Abundances
• Multiple populations in globular clusters: Unified efforts from stellar evolution and chemical evolution models

Cited by in corpus (2)

• The Galactic Bulge exploration IV.: RR~Lyrae stars as traces of the Galactic bar -- 3D and 5D analysis, extinction variation
• RRab variables with identical light-curve shapes at different pulsation periods