Detailed chemical abundances of two stars in the intermediate-age Large Magellanic Cloud ( LMC ) globular cluster NGC 1718 are presented , based on high resolution spectroscopic observations with the MIKE spectrograph .
The detailed abundances confirm NGC 1718 to be a fairly metal-rich cluster , with an average [ Fe / H ] \sim - 0.55 \pm 0.01 .
The two red giants appear to have primordial O , Na , Mg , and Al abundances , with no convincing signs of a composition difference between the two stars—hence , based on these two stars , NGC 1718 shows no evidence for hosting multiple populations .
The Mg abundance is lower than Milky Way field stars , but is similar to LMC field stars at the same metallicity .
The previous claims of very low [ Mg/Fe ] in NGC 1718 are therefore not supported in this study .
Other abundances ( Si , Ca , Ti , V , Mn , Ni , Cu , Rb , Y , Zr , La , and Eu ) all follow the LMC field star trend , demonstrating yet again that ( for most elements ) globular clusters trace the abundances of their host galaxy ’ s field stars .
Similar to the field stars , NGC 1718 is found to be mildly deficient in explosive \alpha -elements , but moderately to strongly deficient in O , Na , Mg , Al , and Cu , elements which form during hydrostatic burning in massive stars .
NGC 1718 is also enhanced in La , suggesting that it was enriched in ejecta from metal-poor AGB stars .