Metallicities and Radial Velocities of SMC Clusters and Field Giants using the CaII Triplet

M.C. PARISI; A. GROCHOLSKI; D. GEISLER; A. SARAJEDINI; J.J. CLARIA

Isla Margarita - Venezuela

Congreso; XII IAU Regional Latin American Meeting of Astronomy; 2007

Centro de Investigaciones de Astronomía

We have obtained near-infrared spectra for approximately 300 red giants in 16 SMC clusters as well as roughly 180 fieldgiants in the areas surrounding the clusters using the FORS2 instrument on the Very Large Telescope. The spectracover a range of   1600 A in the region of the Ca II Triplet (CaT). We use these strong absorption lines to measure radial velocities and equivalent widths, from which  we derive metallicities.We derive mean radial velocities and metallicities of each cluster to  3 km s -1 and 0.05 dex from an average of 6 member per cluster.We will use this information, together with that available for otherclusters studied with the same technique, to analyze the SMC age-metallicity relation.Although most clusters of our sample already have photometric metallicity determinations, they have not beenspectroscopically studied. Consequently, our work provides independent and more reliable information than thephotometric studies and provides for the first time information about cluster radial velocityand membership.We are currentrly analyzing the field giants to compare the chemical evolution in clusters to that of the field and to perform a reliable analysis of the chemical evolution of the SMC.