Galactic abundances: Report of working group 3

Abstract

Abstract. We summarize the various methods and their limitations and strengths to derive galactic abundances from in-situ and remote-sensing measurements, both from ground-based observation s and from instruments in space. Because galactic abundances evolve in time and sp ace it is important to obtain information with a variety of different methods covering different regions from the Very Local Insterstellar M edium (VLISM) to the distant galaxy, and different times throughout the evolution of the galaxy. We discuss the study of the present-day VLISM with neutral gas, pickup ions, and Anomalous Cosmic Rays, the study of the local interstellar medium (ISM) at distances < 1.5 kpc utilizing absorption line me asurements in H I clouds, and the study of galactic cosmic rays, sampling contemporary (~ 15 Myr) s ources in the local ISM within a few kiloparsec of the solar system. Solar system abundances, derived from solar abundances and meteorite studies are discussed in several other chapters o f this volume. They provide samples of matter from the ISM from the time of solar system format ion, about 4.5 Gyr ago. The evolution of galactic abundances on longer time scales is discussed in the context of nuclear synthesis in the various contributing stellar objects.