Bibcode
García-Hernández, D. A.; Zamora, O.; Yagüe, A.; Uttenthaler, S.; Karakas, A. I.; Lugaro, M.; Ventura, P.; Lambert, D. L.
Bibliographical reference
Astronomy and Astrophysics, Volume 555, id.L3, 6 pp.
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7
2013
Journal
Citations
67
Refereed citations
49
Description
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
Related projects
Nucleosynthesis and molecular processes in the late stages of Stellar Evolution
Low- to intermediate-mass (M < 8 solar masses, Ms) stars represent the majority of stars in the Cosmos. They finish their lives on the Asymptotic Giant Branch (AGB) - just before they form planetary nebulae (PNe) - where they experience complex nucleosynthetic and molecular processes. AGB stars are important contributors to the enrichment of the
Domingo Aníbal
García Hernández