The rare light elements in very low metallicity halo stars

The rare light elements, lithium (Li), beryllium (Be), and boron (B) (LiBeB) have a unique and highly coupled history in the Universe. They all are under-abundant compared to their neighbors on the periodic table and they all have origins other than stellar nucleosynthesis. A coordinated analysis of their abundances in very low metallicity stars can advance three scientific goals simultaneously. By estimating the primordial Li abundance it is possible to constrain the baryon-to-photon ratio created in big bang nucleosynthesis. Vends of LiBeB with respect to each other and elements such as iron and oxygen can help determine some of the inner workings of stars, and can constrain models of Galactic Chemical Evolution.; We measured the abundance of 7Li in 43 stars in the halo of the Galaxy. Of these 43 stars, 30 had effective temperatures (5600--6500K) and metallicities ([Fe/H] < -1.5) which were consistent with the Li plateau. We combined our sample with 86 stars in the literature chosen to have the same properties and measured the abundance of the Li plateau to be 2.19 +/- 0.02. We find trends in the data with both T eff and metallicity, as well as a dispersion which indicates these stars have had Li depletion during their lifetime, probably a result of rotational mixing. Taking the dispersion and other factors into account, we estimate that the primordial 7Li abundance is 2.44 +/- 0.18, which is consistent with the predicitions from WMAP of A(Li)p = 2.58 +/- 0.08.; We measured the abundance of Be in 9 stars, most of which are consistent with the literature. We found that G64-37 has a low Be abundance compared to G64-12, HD132475 has an unusually high Be abundance, and that G186-26 is probably similar to a blue straggler.; We detected 6Li in 3 stars out of 10 in our sample. The presence of 6Li in these stars puts an upper limit on the depletion of Li in these stars. Be and 6Li do not scale with metallicity, which indicates that the alpha + alpha process was the dominant formation mechanism for 6Li in the early halo of the Galaxy.