Identification of a new relatively old star cluster in the Small Magellanic Cloud

We present results on the age and metallicity estimates of the astonishingly unstudied Small Magellanic Cloud (SMC) cluster ESO 51-SC09, from CCD BVI photometry obtained at the ESO NTT with the EMMI attached. ESO 51-SC09 turns out to be a relatively small cluster (FWHM = 10 ± 1 pc) located ∼4◦ northward from the galaxy center. We report for the first time a mean cluster age of 7.0 ± 1.3 Gyr and a mean cluster metallicity of [Fe/H] = −1.00 ± 0.15 dex, concluding that ESO 51-SC09 belongs to the group of the oldest SMC clusters. We found that the cluster is projected onto a dominant field stellar population older (age ∼10–13 Gyr) and more metal-poor ([Fe/H] = −1.3 ± 0.2 dex), so that the cluster could reach its current location because of its orbital motion.Fil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin