ON THE IRON CONTENT OF NGC 1978 IN THE LMC: A METAL-RICH, CHEMICALLY HOMOGENEOUS CLUSTER

摘要

We present a detailed abundance analysis of giant stars in NGC 1978, a massive, intermediate-age stellar cluster in the Large Magellanic Cloud, characterized by a high ellipticity and suspected to have a metallicity spread. We analyzed 11 giants, all cluster members, by using high-resolution spectra acquired with UVES/FLAMES at the ESO Very Large Telescope. We find an iron content of [Fe/H] = —0.38 dex with very low σ_([Fe/H])] = 0.07 dex dispersion, a mean heliocentric radial velocity v_r = 293.1 ± 0.9 km s~(-1), and a velocity dispersion σ_(vr) = 3.1 km s~(-1), thus excluding the presence of a significant metallicity, as well as velocity, spread within the cluster.