A spectroscopy-based Age-Metallicity Relation of the SMC

Abstract

The Small Magellanic Cloud (SMC) is the only dwarf galaxy in the Local Group that is known to have formed and preserved populous star clusters continuously over the past 12 Gyr. Due to its proximity ( 60 kpc), stars can be resolved well below the oldest main sequence turnoff points. This facilitates accurate age and metallicity determinations without suffering from the age-metallicity degeneracy. Therefore, the SMC star clusters provide a unique closely spaced set of single-age, single-metallicity tracers to derive a well-sampled age-metallicity relation required for the understanding of the star formation history of this satellite galaxy. Up to date spectroscopically based metallicity estimates exist only for the small number of 7 clusters (Da Costa & Hatzidimitriou 1998). Our project now more than doubles the available data set by the observation of 10 additional clusters.