A first HIPPARCOS contribution to the light elements problem

Abstract

{The interpretation of the observations of the light elements requires the knowledge of the evolutionary status of the observed stars. The HIPPARCOS accurate parallaxes solve several cases of ambiguous status. For example, it is shown that, since HD 84937 is a subgiant, its (6Li) abundance is compatible with the predictions of the standard models of Big Bang nucleosynthesis and of stellar evolution. Also the non-detection of (6Li) in Population II dwarfs is in agreement with these predictions. In order to reach more precise lithium abundances, more reliable temperature scales, and, more generally, better stellar models, are necessary. } Based on data from the ESA Hipparcos astrometry satellite