期刊
ASTROPHYSICAL JOURNAL LETTERS
卷 767, 期 1, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/2041-8205/767/1/L19
关键词
open clusters and associations: individual (NGC 6819); stars: abundances; stars: chemically peculiar
资金
- NSF via the CSUURE REU program [AST-0850564]
- NSF [AST-1211621, AST-1211699]
- Direct For Mathematical & Physical Scien
- Division Of Astronomical Sciences [1211621, 1211699, 0850564] Funding Source: National Science Foundation
WIYN/HYDRA spectra in the Li 6708 angstrom region have been obtained for 332 probable members of the old open cluster, NGC 6819. Preliminary analysis shows a pattern of Li depletion from the top of the turnoff to the base of the giant branch. Starting 1 mag below the level of the clump, all brighter giants have A(Li) below 1.0, with most having upper limits below 0.5. Star W007017, located below the first-ascent red giant bump is Li-rich with A(Li) = 2.3. As a highly probable single-star astrometric and radial-velocity cluster member, its discrepant asteroseismic membership could be a by-product of the processes that triggered Li enhancement. Its color-magnitude diagram location is consistent with only one proposed enhanced mixing process among first-ascent red giants.
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