|
Description
We have observed 15 red giant stars in the relatively massive, metal-poor globular cluster NGC 4833 using the Magellan Inamori Kyocera Echelle spectrograph at Magellan. We calculate stellar parameters for each star and perform a standard abundance analysis to derive abundances of 43 species of 39 elements, including 20 elements heavier than the iron group. We derive <[Fe/H]>=-2.25+/-0.02 from FeI lines and <[Fe/H]>=-2.19+/-0.013 from FeII lines. We confirm earlier results that found no internal metallicity spread in NGC 4833, and there are no significant star-to-star abundance dispersions among any elements in the iron group (19=<Z=<30). We recover the usual abundance variations among the light elements C, N, O, Na, Mg, Al, and possibly Si. The heavy-element distribution reflects enrichment by r-process nucleosynthesis ([Eu/Fe]=+0.36+/-0.03), as found in many other metal-poor globular clusters. We investigate small star-to-star variations found among the neutron-capture elements, and we conclude that these are probably not real variations. Upper limits on the Th abundance, log{epsilon} (Th/Eu)<-0.47+/-0.09, indicate that NGC 4833, like other globular clusters where Th has been studied, did not experience a so-called actinide boost.
|
