Distances to Populous Clusters in the LMC via the K-Band Luminosity of the Red Clump

Abstract

We present results from a study of the distances and distribution of a sample of intermediate-age clusters in the Large Magellanic Cloud. Using deep near-infrared photometry obtained with ISPI on the CTIO 4m, we have measured the apparent K-band magnitude of the core helium burning red clump stars in 17 LMC clusters. We combine cluster ages and metallicities with the work of Grocholski & Sarajedini to predict each cluster's absolute K-band red clump magnitude, and thereby calculate absolute cluster distances. An analysis of these data shows that the cluster distribution is in good agreement with the thick, inclined disk geometry of the LMC, as defined by its field stars. We also find that the old globular clusters follow the same distribution, suggesting that the LMC's disk formed at about the same time as the globular clusters, ~ 13 Gyr ago. Finally, we have used our cluster distances in conjunction with the disk geometry to calculate the distance to the LMC center, for which we find (m-M)o = 18.40 +/- 0.04_{ran} +/- 0.08_{sys}, or Do = 47.9 +/- 0.9 +/- 1.8 kpc.

31 pages including 5 figures and 7 tables. Accepted for publication in the August 2007 issue of AJ

References in corpus (4)

• A new Cepheid distance to the maser-host galaxy NGC 4258 and its implications for the Hubble Constant
• Calcium II Triplet Spectroscopy of LMC Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters
• Physical parameters of 15 intermediate-age LMC clusters from modelling of HST colour-magnitude diagrams
• On the Iron content of NGC 1978 in the LMC: a metal rich, chemically homogeneous cluster

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• Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud: II. Relative ages and distances for six ancient globular clusters
• Explanation of a special color-magnitude diagram of star cluster NGC 1651 from different models
• Using Red Clump Stars to Decompose the Galactic Magnetic Field with Distance
• On the self-consistent physical parameters of LMC intermediate-age clusters