TY - JOUR
T1 - The discovery of a Li/Na-rich giant star in Omega Centauri
T2 - Formed from the pure ejecta of super-AGB stars?
AU - Mucciarelli, A.
AU - Monaco, L.
AU - Bonifacio, P.
AU - Salaris, M.
AU - Fu, X.
AU - Villanova, S.
N1 - Funding Information:
Acknolw edgements. We thank the anonymous referee for his/her useful comments and suggestions. L.M. acknowledges support from “Proyecto interno” of the Universidad Andres Bello. P.B. acknowledges financial support from the Scientific Council of Observatoire de Paris and from the action fédératrice “Exploitation Gaia”. S.V. gratefully acknowledges the support provided by Fondecyt reg. n. 1170518.
Publisher Copyright:
© ESO 2019.
PY - 2019/3/1
Y1 - 2019/3/1
N2 -
We report the discovery of two Li-rich giant stars (fainter than the red giant branch (RGB) 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, which 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 M
™
. 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 having 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.
AB -
We report the discovery of two Li-rich giant stars (fainter than the red giant branch (RGB) 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, which 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 M
™
. 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 having 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.
KW - Globular clusters: individual: Omega Centauri
KW - Stars: abundances
KW - Techniques: spectroscopic
UR - http://www.scopus.com/inward/record.url?scp=85062860026&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/201834497
DO - 10.1051/0004-6361/201834497
M3 - Article
AN - SCOPUS:85062860026
SN - 0004-6361
VL - 623
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A55
ER -