Ordinary stars, i.e., solar-type stars, have extra-ordinary deaths following their evolution as asymptotic giant branch (AGB) stars. Central to their final evolution is a strong stellar wind which removes substantial amounts of matter from their surfaces. The mechanisms behind this mass loss are still not fully understood. Therefore, the evolution of these stars and their roles in the nucleosynthesis and the cosmic gas/dust cycle remain uncertain. The wind also plays an important role during the formation of the spectacular planetary nebulae. We are pursuing a systematic study of the mass-loss properties of these stars. We have published extensive surveys in molecular radio lines, performed radio interferometric observations, obtained large amounts of Herschel data, used novel observing methods to measure circumstellar scattered stellar light, 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. These provide reliable mass-loss rates, and circumstellar gas and dust compositions. 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.
Professor vid Radio Astronomy and Astrophysics
Funding Chalmers participation during 2012–2014 with 900,000.00 SEK