Simultaneous (age, metallicity) estimates of the Hyades open cluster from three binary systems

Three binary systems in the Hyades open cluster, with known metallicity and good Johnson photometric data are used to test the validity of three independent sets of stellar evolutionary tracks. A statistical method is described and applied to the colour-magnitude diagram of the six selected components, giving rise to $\chi^2$-contours in the age-metallicity plane. The effects of the Hipparcos parallaxes on these confidence regions are studied for these binaries through a comparison with very accurate but older orbital parallaxes. Independent simultaneous age-metallicity estimates are given and compared with observational constraints (see Lastennet et al. 1999, astro-ph/9905273, for more details).