Homogeneous metallicities for 14 old LMC globular clusters based on their fundamental mode RR Lyrae stars

Abstract

ABSTRACT We present the first internally consistent set of [Fe/H] values for 14 of the 15 old globular clusters in the Large Magellanic Cloud (LMC). We make use of periods and amplitudes of fundamental mode (ab-type) RR Lyrae stars in the vicinity of these LMC clusters, mostly taken from the Optical Gravitational Lensing Experiment (OGLE) data base, in order to calculate metallicities for the clusters. Our data set contains a total of 417 ab-type cluster RR Lyrae stars (289 from OGLE and the rest from the literature) and yields a set of homogeneous metallicities for 14 old LMC globular clusters all on the Zinn and West scale. No previously published work contains metallicities for as many of the old LMC globular clusters as presented herein. An analysis of a subset of our abundances compared with seven other metallicity studies in the peer-reviewed literature indicates very little overall agreement between these [Fe/H] values suggesting that significantly more effort needs to be devoted to measuring internally consistent [Fe/H]s for the old LMC globular clusters.