The Chemical Enrichment History of the Small Magellanic Cloud and its Gradients

We present stellar metallicities derived from Ca II triplet spectroscopy in over 350 red giant branch stars in 13 fields distributed in different positions in the Small Magellanic Cloud, ranging from ~1° to ~4° from its center. In the innermost fields, the average metallicity is [Fe/H] ~-1. This value decreases when we move away toward outermost regions. This is the first detection of a spectroscopic metallicity gradient in this galaxy. We show that the metallicity gradient is related to an age gradient, in the sense that more metal-rich stars, which are also younger, are concentrated in the central regions of the galaxy.

Based on observations collected at the European Southern Observatory, Chile, within the observing programs 074.B-0446.