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

## TL;DR

This paper reports the discovery of Li-rich giant stars in Omega Centauri, suggesting they may have formed from super-AGB star ejecta or through internal mixing, providing insights into stellar evolution and nucleosynthesis.

## Contribution

It presents the first identification of Li-Na-rich giants in Omega Centauri and discusses their possible formation from super-AGB star ejecta or binary interactions.

## Key findings

- Discovery of two Li-rich giants with high Na abundance.
- Li-Na-rich star possibly formed from super-AGB ejecta.
- Chemical signatures provide insights into super-AGB star processes.

## Abstract

We report the discovery of two Li-rich giant stars (fainter than the red giant branch bump) in the stellar system Omega Centauri using GIRAFFE-FLAMES spectra. These two stars have A(Li)=1.65 and 2.40 dex and they belong to the main population of the system ([Fe/H]=--1.70 and --1.82, respectively). The most Li-rich of them (#25664) has [Na/Fe]=+0.87 dex that is ~0.5 dex higher than those measured in the most Na-rich stars of Omega Centauri of similar metallicity. The chemical abundances of Li and Na in #25664 can be qualitatively explained by deep extra mixing efficient within the star during its RGB evolution or by super-asymptotic giant branch (AGB) stars with masses between ~7 and 8 Msun. In the latter scenario, this Li-Na-rich star could be formed from the pure ejecta of super-AGB stars before the dilution with pristine material occurs, or, alternatively, be part of a binary system and experienced mass transfer from the companion when this latter evolved through the super-AGB phase. In both these cases, the chemical composition of this unique object could allow to look for the first time at the chemical composition of the gas processed in the interior of super-AGB stars.