Age determinations of main-sequence stars: combining different methods

We have determined the age of a sample of nearby main-sequence stars with s pectral types B9-K9. We have derived the stellar ages from five different a ge estimators: the location in the HR diagram compared to theoretical isoch rones, the rotational velocity, the strength of chromospheric calcium emiss ion lines, the stellar metallicity, and their space velocity. New calibrati ons consistent with recent theoretical isochrones are provided for the last four indicators. For hot stars, isochrones are the best indicator, while s tellar rotation is best for cool stars. However, many stars require in fact a combination of different methods to properly bracket their actual age. W e also discuss the uncertainties involved, in particular those in using iso chrones, and we find that these uncertainties are often underestimated in t he literature.