Very Metal-poor Stars in the Solar Vicinity: Age Determination

Abstract The ages of the oldest and most metal-poor stars in Milky Way bear important information on age universe its standard model. We analyze a sample 28 extremely field solar vicinity culled from literature carefully determine their ages. To this aim, we critically make use Gaia data to derive distances associated uncertainties. Particular attention has been paid estimate reddening effect derivation stellar employed different reddenings superimpose isochrones sources stars' color–magnitude diagram built up with photometric systems. highlight subtle metallicity effects when using Johnson photometry for low-metallicity finally adopt photometry. An automatic fitting method is devised assign each individual star taking into account uncertainties input parameters. mean turns out be 13.9 ± 0.5 Gyr Padova isochrones, 13.7 0.4 BASTI isochrones. found also group very ([Fe/H] = −2.7 −2.0 dex) relatively young ages, range 8–10 Gyr.