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Astron. Astrophys. 358, L49-L52 (2000)

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Letter to the Editor

Episodic lithium production by extra-mixing in red giants

P.A. Denissenkov 1,2 and A. Weiss 2

1 Astronomical Institute of the St. Petersburg University, Bibliotechnaya Pl. 2, Petrodvorets, 198904 St. Petersburg, Russia
2 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany

Received 17 April 2000 / Accepted 12 May 2000


The recent discovery of low-mass red giants with enhanced atmospherical Li abundance in galactic low-metallicity stellar clusters adds to the mysterious phenomenon of the Li-rich giants. We propose a combined scenario for the Li-enrichment: engulfing a giant planet (or brown dwarf) by a red giant (external source) activates inside the giant the "7Be-mechanism" producing Li internally. This episodical Li-production can happen at any time on the red giant branch and is naturally followed by Li-depletion as is observed. Limitations of our scenario are discussed as well.

Key words: stars: chemically peculiar – stars: evolution – stars: interiors – stars: late-type – stars: rotation

Send offprint requests to: A. Weiss (weiss@mpa-garching.mpg.de)

© European Southern Observatory (ESO) 2000

Online publication: June 8, 2000