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

Letter to the Editor

Episodic lithium production by extra-mixing in red giants

P.A. Denissenkov ^1,2 and A. Weiss <sup>2

1</sup> 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

Abstract

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)

SIMBAD Objects

Contents

• 1. Introduction
• 2. Extra-mixing in red giants
• 3. A solution to the problem of Li-rich giants
• 4. Conclusion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: June 8, 2000
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