Ordinary stars, i.e., solar-type stars, have extra-ordinary deaths. Central to this final evolution on the asymptotic giant branch is a stellar wind which removes substantial amounts of matter from the stellar surface. The mechanisms behind this mass loss are still not fully understood. Therefore, the evolution of these stars and their roles in the cosmic gas/dust cycle remain uncertain. The winds also play an important role during the formation of the spectacular planetary nebulae (PNe). We are pursuing systematic studies of the mass-loss properties of these stars, and of the chemistry and the morphological evolution of their winds. We have published extensive surveys in molecular radio lines, performed radio interferometric observations, obtained large amounts of Herschel data, used novel observing methods, and obtained an extensive census of the AGB populations in Local Group galaxies. Radiative transfer modelling of molecular line and dust continuum emission have been done successfully for large data sets. We propose here a continued detailed study of the properties and consequences of mass loss on and beyond the AGB, based on a research programme centered on the use of the new observational facility ALMA. Central issues are the mass-loss dependence on metallicity, the mass-loss mechanism, the mechanism behind the formation of PNe (e.g. the importance of binaries), and isotope ratios as probes of stellar evolution and galactic star formation histories.
Professor vid Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Funding Chalmers participation during 2015–2018