期刊
ASTRONOMY & ASTROPHYSICS
卷 555, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201321818
关键词
stars: AGB and post-AGB; stars: abundances; stars: evolution; nuclear reactions, nucleosynthesis, abundances; stars: atmospheres; stars: late-type
资金
- Spanish Ministry of Economy and Competitiveness [AYA-2011-27754, AYA-2011-29060]
- Austrian Science Fund (FWF) [P 22911-N16]
- NCI National Facility at the ANU
- ARC [FT110100475, FT100100305]
- Monash University
- Robert A. Welch Foundation of Houston, Texas [F-634]
- Australian Research Council [FT100100305] Funding Source: Australian Research Council
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 epsilon (Li) similar to 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 Ne-22 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 Ne-22 neutron source dominates the s-process nucleosynthesis.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据