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We report the discovery of two Li-rich giant stars (fainter than the redgiant branch bump) in the stellar system Omega Centauri using GIRAFFE-FLAMESspectra. These two stars have A(Li)=1.65 and 2.40 dex and they belong to themain population of the system ([Fe/H]=--1.70 and --1.82, respectively). Themost Li-rich of them (#25664) has [Na/Fe]=+0.87 dex that is ~0.5 dex higherthan those measured in the most Na-rich stars of Omega Centauri of similarmetallicity. The chemical abundances of Li and Na in #25664 can bequalitatively explained by deep extra mixing efficient within the star duringits RGB evolution or by super-asymptotic giant branch (AGB) stars with massesbetween ~7 and 8 Msun. In the latter scenario, this Li-Na-rich star could beformed from the pure ejecta of super-AGB stars before the dilution withpristine material occurs, or, alternatively, be part of a binary system andexperienced mass transfer from the companion when this latter evolved throughthe super-AGB phase. In both these cases, the chemical composition of thisunique object could allow to look for the first time at the chemicalcomposition of the gas processed in the interior of super-AGB stars.

The discovery of a Li-Na-rich giant star in Omega Centauri: formed from the pure ejecta of super-AGB stars?