The lithium content of the galactic halo stars

¹ G. Observatory, 1290 Sauverny, Switzerland
² LATT., CNRS UMR 5572, 14 Av. E. Belin, 31400 Toulouse, France
³ European Southern Observatory, Garching b. Muenchen, Germany

Abstract

Thanks to the accurate determination of the baryon density of the Universe by the recent cosmic microwave background experiments, updated predictions of the standard model of Big Bang nucleosynthesis yield the initial abundances of the primordial light elements with an unprecedented precision (Bennet et al. 2003; Spergel et al. 2003; Coc et al. 2004; Cyburt 2004; Serpico et al. 2004). In the case of ⁷Li, the CMB+SBBN value is significantly higher than the generally reported abundances for Pop II stars along the Spite plateau. 
Here, we report on the very recent results we obtained by revisiting a large sample of literature Li data in halo stars that we assembled following some strict criteria on the quality of the original analyses published from the early 90 s onwards. We put a strong emphasis on the temperature scale and reddening issues, and on the determination of the evolutionary status of each of our sample stars. Using our “best" (i.e. most consistent) set of temperatures we discuss the resulting mean Li value along the plateau for the dwarf stars on one hand and for the turnoff and subgiant stars on the other hand.