Ca II Triplet Spectroscopy of Small Magellanic Cloud Red Giants. III. Abundances and Velocities for a Sample of 14 Clusters

M.C. PARISI; D. GEISLER; J.J. CLARIÁ; S. VILLANOVA; N. MARCIONNI; A. SARAJEDINI; A.J. GROCHOLSKI

ASTRONOMICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2015 vol. 149 p. 154 - 165

0004-6256

We obtained spectra of red giants in 15 Small Magellanic Cloud (SMC) clu s- ters in the region of the CaII lines with FORS2 on the Very Large Teles cope (VLT). We determined the mean metallicity and radial velocity with mea n er- rors of 0.05 dex and 2.6 km s − 1 , respectively, from a mean of 6.5 members per cluster. One cluster (B113) was too young for a reliable metallicity de termina- tion and was excluded from the sample. We combined the sample studie d here with 15 clusters previously studied by us using the same technique, a nd with 7 clusters whose metallicities determined by other authors are on a sc ale similar to ours. This compilation of 36 clusters is the largest SMC cluster sample currently available with accurate and homogeneously determined metallicities. W e found a high probability that the metallicity distribution is bimodal, with potentia l peaks at -1.1 and -0.8 dex. Our data show no strong evidence of a metallicity gradient in the SMC clusters, somewhat at odds with recent evidence from Ca T spectra of a large sample of field stars (Dobbie et al. 2014). This may be revealing possible differences in the chemical history of clusters and field stars. Our c lusters show a significant dispersion of metallicities, whatever age is considered, w hich could be reflecting the lack of a unique AMR in this galaxy. None of the chemic al evolution models currently available in the literature satisfactorily re presents theglobal chemical enrichment processes of SMC clusters