Chemical analysis of the Small Magellanic Cloud Main Body

B.J. DE BORTOLI; M.C. PARISI; L.P. BASSINO; D. GEISLER; B. DIAS; G. GIMENO; M.S. ANGELO; F. MAURO

Seúl

Congreso; Gemini Observatory Science Meeting; 2022

We present results of the chemical study of 6 star clusters in the Main Body of the Small Magellanic Cloud (SMC). Near infrared spectra were obtained with GMOS (GEMINI-S) in the region of Calcium Triplet (CaT) lines of red giant stars belonging to the star clusters and their surrounding fields. We measured radial velocities and equivalent width of the CaT lines and determined the mean cluster and field metallicities. We enlarged this sample with information available in the literature for star clusters studied with the same technique, obtaining a final sample of 57 star clusters with accurate CaT metallicities. We found a high probability that the metallicity distribution of the Main Body clusters is bimodal with probable metal-rich and metal-poor cluster groups, having mean metallicities -0.8 dex and -1.15 dex, respectively.On the other hand, Main Body field stars show a unimodal metallicity distribution peaking at [Fe=H] ~ -1 dex, in agreement with previous works. Metal-rich clusters present a clear age-metallicity relation, while metal-poor clusters present no chemical enrichment throughout the life of the galaxy. We present observational evidence that the chemical enrichment is complex in the SMC Main Body and two potential cluster groups with possible different origins could be coexisting in it.