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HD 21080


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A search for lithium-rich giant stars
Lithium abundances or upper limits have been determined for 644 brightG-K giant stars selected from the DDO photometric catalog. Two of thesegiants possess surface lithium abundances approaching the 'cosmic' valueof the interstellar medium and young main-sequence stars, and eight moregiants have Li contents far in excess of standard predictions. At leastsome of these Li-rich giants are shown to be evolved to the stage ofhaving convectively mixed envelopes, either from the direct evidence oflow surface carbon isotope ratios, or from the indirect evidence oftheir H-R diagram positions. Suggestions are given for the uniqueconditions that might have allowed these stars to produce or accrete newlithium for their surface layers, or simply to preserve from destructiontheir initial lithium contents. The lithium abundance of the remainingstars demonstrates that giants only very rarely meet the expectations ofstandard first dredge-up theories; the average extra Li destructionrequired is about 1.5 dex. The evolutionary states of these giants andtheir average masses are discussed briefly, and the Li distribution ofthe giants is compared to predictions of Galactic chemical evolution.

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Osservazione e dati astrometrici

Costellazione:Fornace
Ascensione retta:03h22m42.39s
Declinazione:-38°27'32.5"
Magnitudine apparente:8.43
Distanza:323.625 parsec
Moto proprio RA:42.5
Moto proprio Dec:17
B-T magnitude:9.797
V-T magnitude:8.543

Cataloghi e designazioni:
Nomi esatti   (Edit)
HD 1989HD 21080
TYCHO-2 2000TYC 7568-1065-1
USNO-A2.0USNO-A2 0450-01158087
HIPHIP 15733

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