POPULATION-II LI-6 AS A PROBE OF NUCLEOSYNTHESIS AND STELLAR STRUCTURE AND EVOLUTION

We discuss the importance of Population II Li-6 as a diagnostic for mo dels of primordial nucleosynthesis, cosmic-ray nucleosyntheses in the early Galaxy, and the structure and evolution of metal-poor solar-type stars. The observation of Li-6 in the subdwarf HD 84937 is shown to b e consistent with the existing Population II LiBeB data within the con text of a simple three-component model: (1) standard big bang nucleosy nthesis, (2) Population II cosmic-ray nucleosynthesis, (3) standard (n onrotating) stellar LiBeB depletion. If this interpretation is correct , we predict a potentially detectable boron abundance for this star: B /H approximately 2 x 10(-12). Subsequent Population II LiBeB observati ons, and in particular further observations of Population II Li-6, are shown to be crucial to our understanding of the primordial and early galactic creation and destruction mechanisms for light elements.