The relation of metal-poor stars to nearby solar analogues

Abstract

Sun-like dwarf stars in the solar neighborhood reflect ages, an ``average'' chemical evolution, and departures from that average. We show the chemical, and kinematic properties of four groups of Sunlike dwarfs form a continuum related to age. We plot [Fe/H] vs. age, as well as kinematical values for the four groups. The vertical (negative) scatter in [Fe/H] increases with age in a systematic way: as the age increases, [Fe/H] decreases. The sets of Solar and metal-poor stars in the solar neighborhood are related by distributions in [Fe/H] vs. age, as well as in Galactic position (XYZ) and velocity space (UVW). Among the samples there are no clusters of points that set one sample apart from the others. The distributions vary slowly from one set to the next, suggesting a mixture of stellar populations. A plot in Energy vs angular momentum phase space, with coordinate origin moved to the Galactic center, highlights different aspects of the kinematics of the four groups of stars. We finally compare the kinematic properties of these four groups with those of two sets of ultra metal-poor stars.Comment: 8 pages, 6 figure