Abundances in Stellar Populations

Stellar abundances are reviewed with emphasis on large-scale effects which may yield clues to galactic structure and evolution. Spectroscopic and indirect photoelectric abundance criteria are discussed, and utilized.The abundance statistics of nearby galactic disk stars, dominated by M dwarfs, but observed at spectral types F and GV and K III, suggest a weak age-abundance relationship with a substantial dispersion at any time. Very metal-poor stars are extremely rare. Spatial abundance gradients, with higher metal abundances occurring nearer the galactic centre, are indicated. Disk abundance gradients are prevalent for light elements in other Sb and Sc galaxies.The confusing status of supermetallicity is again reviewed. The super-metal-rich (SMR) giants (like μ Leo) are either over-abundant because of self-N-enrichment (from C–N–O processing?)and boundary-temperature cooling, or are really SMR. Each case may be reasonably argued. The old galactic clusters M67 and NGC 183 seem, by recent indirect acclaim, to be only slightly more metal-rich than the Sun. The Spinrad-Taylor data on the M67 giants would still seem to superficially suggest overabundances in Na and Mg, but other interpretations are possible.SMR dwarfs, like HR 72, and subgiants, like 31 Aql are surely very old, and have metal abundances larger than the Hyades. However, they are, by number, only ≈ 5% of the local main sequence.The galactic halo star tracers – red giants and RR Lyrae stars, have been observed extensively, lately. There is some indication of an abundance gradient from 5 or 10 kpc galactocentric radius out to r ~ 100 kpc. The most metal-poor stars observed in the Draco system are about 1000 times less abundant in heavy elements than is the Sun, and much of the galactic disk.Abundances in other galaxies, as a function of their total mass, and stellar/gaseous composition are also reviewed. There is a clear dependence of abundance on galaxian total mass.