Bibcode
García-Hernández, D. A.; Zamora, O.; Yagüe, A.; Uttenthaler, S.; Karakas, A. I.; Lugaro, M.; Ventura, P.; Lambert, D. L.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 555, id.L3, 6 pp.
Fecha de publicación:
7
2013
Revista
Número de citas
67
Número de citas referidas
49
Descripción
We report the first spectroscopic identification of massive Galactic
asymptotic giant branch (AGB) stars at the beginning of the thermal
pulse (TP) phase. These stars are the most Li-rich massive AGBs found to
date, super Li-rich AGBs with log ɛ (Li) ~ 3-4. The high Li
overabundances are accompanied by weak or no s-process element (i.e. Rb
and Zr) enhancements. A comparison of our observations with the most
recent hot bottom burning (HBB) and s-process nucleosynthesis models
confirms that HBB is strongly activated during the first TPs but the
22Ne neutron source needs many more TP and third dredge-up
episodes to produce enough Rb at the stellar surface. We also show that
the short-lived element Tc, usually used as an indicator of AGB
genuineness, is not detected in massive AGBs, which is in agreement with
the theoretical predictions when the 22Ne neutron source
dominates the s-process nucleosynthesis.
Appendix A is available in electronic form at http://www.aanda.org
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