K-Band Red Clump Distances to the Large Magellanic Cloud Clusters Hodge 4 and NGC 1651
/ Authors
/ Abstract
We present near-infrared color-magnitude diagrams (CMDs) for the Large Magellanic Cloud (LMC) star clusters Hodge 4 and NGC 1651, revealing the helium-burning red clump (RC) stars for the first time in the JK passbands. From these diagrams, which extend to K ∼ 19, and existing optical CMDs that reveal the clusters' main-sequence turnoffs, we determine the following cluster parameters. For Hodge 4, we estimate a metallicity of [Fe/H] = -0.17 ± 0.04, an age of 1.7 ± 0.3 Gyr, and a RC absolute magnitude of MK(RC) = -1.64 ± 0.17. Along with an adopted reddening of E(J-K) = 0.03 ± 0.01 based on the Burstein & Heiles and Schlegel et al. reddening maps, we find a distance of (m - M)0 = 18.52 ± 0.17 for Hodge 4. In the case of NGC 1651, we derive [Fe/H] = -0.07 ± 0.10, an age of 1.8 ± 0.3 Gyr, MK(RC) = -1.56 ± 0.12, E(J-K) = 0.06 ± 0.01, and (m - M)0 = 18.55 ± 0.12, all measured in the same manner as for Hodge 4. Based on these two clusters, we calculate a mean LMC distance of (m - M)0 = 18.54 ± 0.10.
Journal: The Astronomical Journal
DOI: 10.1086/343776