Lithium isotopic abundances in old stars

Abstract

Lithium is an element of great importance from a cosmological point of view. Observations of its light isotope Li-6 are very delicate and in the literature, detections for only a handful of metal-poor stars are found. High quality spectra (S/N similar to 450, R similar to 100000) of the Li I 670.8 nm resonance line of six metal-poor stars, taken at the Subaru telescope, are being analysed. The results based on the still early stage of the analysis suggest one possible detection and four possible upper limits (including the two most metal-poor stars in the sample) for Li-6. The observed spectra of the remaining star suggest that there is very little Li-6, if any at all.