Red giant abundances in NGC 2808

UVES spectra for 31 stars and GIRAFFE spectra for the other giants were analyzed with the same procedures used for about 2500 giants in 23 GCs in our FLAMES survey, deriving abundances of Fe, O, Na, Mg, Si, Ca, Ti, Sc, Cr, Mn, and Ni. Iron, elements from {alpha} capture, and those in the Fe group do not show intrinsic scatter.

On our UVES scale, the metallicity of NGC 2808 is [Fe/H]=-1.29+/-0.005+/-0.034 (+/-statistical+/-systematic error) with {sigma}=0.030 (31 stars). The main features related to proton-capture elements are retrieved, but the improved statistics and the smaller associated internal errors allow us to uncover five distinct groups of stars along the Na-O anticorrelation. We observe large depletions in Mg, anticorrelated with enhancements of Na and also Si, suggestive of unusually high temperatures for proton captures.