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

Abstract

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 SMC, ranging from $\sim$1\arcdeg\@ to $\sim$4\arcdeg\@ from its center. In the innermost fields the average metallicity is [Fe/H] $\sim -1$. This value decreases when we move away towards outermost regions. This is the first detection of a 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.