A FIRST HIPPARCOS CONTRIBUTION TO THE LIGHT-ELEMENTS PROBLEM

The interpretation of the observations of the light elements requires the knowledge of the evolutionary status of the observed stars. The HI PPARCOS accurate parallaxes solve several cases of ambiguous status. F or example, it is shown that, since HD 84937 is a subgiant, its Li-6 a bundance is compatible with the predictions of the standard models of Big Bang nucleosynthesis and of stellar evolution. Also the non-detect ion of Li-6 in Population II dwarfs is in agreement with these predict ions. In order to reach more precise lithium abundances, more reliable temperature scales, and, more generally, better stellar models, are n ecessary.