And if Thick-Disk Stars Were the First Stars?

Abstract.

Observational evidence for a multi-component Galactic halo and the absence of any one-to-one age-metallicity relation implies that the mere finding of an ultra metal-poor star must be considered as a weak argument for a “first star” in terms of age. The Milky Way’s thick-disk population, by contrast, is identifiable as an extremely old population and as such most appropriate to provide reliable constraints on the age of the Galaxy.