2005A&A...436L...9C

We present here the first measurements of sulphur abundances in extragalactic stars. We make use of high resolution spectra, obtained with UVES at the ESO 8.2m Kueyen telescope, of three giants of the Globular Cluster Terzan 7, which belongs to the Sagittarius dwarf galaxy. We measure the sulphur abundances using the lines of SI multiplet 1. The S/Fe ratios for all three stars are nearly solar, thus considerably lower than what is found in Galactic stars of comparable iron content ([Fe/H]~-0.50). This finding is in keeping with the abundances of other α-chain elements in this cluster and in Sagittarius and other dSphs in general. These low α-chain elements to iron ratios suggest that Sagittarius and its Globular Clusters have experienced a low or bursting star-formation rate. Our sulphur abundances imply <log(S/O)≥-1.61 which is comparable to what is found in many HII regions of similar oxygen content, and is slightly lower than the solar value (log(S/O)_☉=-1.51). These are also the first measurements of sulphur abundances in a Globular Cluster, thus a direct comparison of Terzan 7 and Galactic Globular Clusters is not possible yet. However our analysis suggests that the lines of SI multiplet 1 should be measurable for other Globular Clusters at least down to a metallicity ~-1.5.