  We employ a new Infrared Flux Method (IRFM) temperature scale (Ramirez &
Melendez 2005, ApJ 626, 446; ApJ 626, 465) in order to determine Li, O, and Fe
NLTE abundances in a sample of relatively unevolved (dwarfs, turn-off,
subgiants) metal-poor stars. We show that the analysis of the permitted OI
triplet and FeII lines leads to a plateau in [OI/FeII] over the broad
metallicity range -3.2 < [Fe/H] < -0.7, independent of temperature and
metallicity, and with a star-to-star scatter of only 0.1 dex. The Li abundance
in halo stars is also found to be independent of temperature and metallicity
(Spite plateau), with a star-to-star scatter of just 0.06 dex over the
metallicity range -3.4 < [Fe/H] < -1. Our Li abundance (Melendez & Ramirez
2004, ApJ 615, L33) is higher than previously reported values, but still lower
than the primordial abundance suggested by WMAP data and BBN.

Astrophysics