The Disk Populations in the [Mg/H]-[Fe/Mg] Plane

The disk populations' metal abundance degeneracy is shown to be considerably relaxed in a two-dimensional presentation of their chemical properties. Assuch, the metallicities of a sample of nearby F- and G-stars aregiven in terms of magnesium abundances along the abscissa andiron-to-magnesium abundance ratios perpendicular to that. Incombination with stellar age estimates and kinematics the disk populationsturn out to be fairly well separable in this abundance plane,which in turn allows to address a number of important issues on theMilky Way's history. This revised version was published online in July 2006 with corrections to the Cover Date.