Lithium-rich giants in the Sagittarius dSph Tidal Streams

Abstract

The nature and origin of Lithium rich giant stars is still matter of debate. In the contest of our spectroscopic survey of giants in the tidal streams of the Sagittarius dwarf spheroidal (dSph) galaxy, we present the serendipitous discovery of 2 super Li-rich stars (A(Li)$>$3.5-4.0). Besides D461 in Draco, these are the only Li-rich stars known in a Local Group dSph galaxy. The high Li abundance and the low mass of these stars support their origin as due to fresh Li production in the stars associated with some kind of extra-mixing process.

5 pages, 4 figures, 2 tables. Proceedings of the workshop "XXI Century challenges for stellar evolution", held in Cefalu' (Sicily, Italy), August 29 - September 2, 2007; S. Cassisi and M. Salaris Eds. To be published in Mem. SAIt Vol. 79 No. 2