Present-day abundances from OB stars

Abstract

Massive late O- and early B-type stars are ideal indicators for present-day elemental abundances in star-forming regions in the solar neighbourhood and throughout wide parts of the Milky Way disk. They complement other classical indicators such as emission line spectra of H ii regions while providing abundance data of high accuracy and precision. An overview of the progress made in deriving abundances for a wide range of chemical species from spectra in the UV, optical, and near-IR domains is given. Results for OB-star populations in the Milky Way are discussed. These provide observational present-day boundary conditions for the study of Galactochemical evolution and point to a birthplace of the solar system at a galactocentric radius of 5 to 6 kpc with subsequent migration to its current location.