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

PIATTI, ANDRÉS E.

The Astrophysical Journal Letters

IOP PUBLISHING LTD.

Año: 2012 vol. 756 p. 32 - 35

2041-8205

We present results on the age and metallicity estimates of the astonishingly unstudied SMC cluster ESO,51-SC09, from CCD $BVI$ photometry obtained at the ESO NTTwith the EMMI attached. ESO,51-SC09 turns out to be a relatively small cluster (FWHM = (10 $pm$ 1) pc)located $sim$ 4$degr$ northward from the galaxy center.We report for the first time a mean cluster age of (7.0 $pm$ 1.3) Gyr and a meancluster metallicity of [Fe/H] = (-1.00 $pm$ 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 $sim$ 10-13 Gyr) and more metal-poor ([Fe/H] = -1.3$pm$0.2 dex), so that the cluster could reachits current location because of its orbital motion.