(Re)solving Mysteries of Convection and Mass Loss of AGB Stars: What New Models and Observations Tell Us About Long-Standing Problems
(Oct 27, 2016)DOI: 10.5281/zenodo.154673
Abstract
The recent progress in high-spatial-resolution techniques, spanning
wavelengths from the visual to the radio regime, is leading to new valuable
insights into the complex dynamical atmospheres of Asymptotic Giant Branch
(AGB) stars and their wind forming regions. Striking examples are images of
asymmetries and inhomogeneities in the photospheric and dust-forming layers
which vary on time-scales of months. These features are probably related to
large-scale convective flows predicted by 3D star-in-a-box models. Furthermore,
high-resolution observations make it possible to measure dust condensation
distances, and they give information about the chemical composition and sizes
of dust grains in the close vicinity of cool giants. These are essential
constraints for building realistic models of wind acceleration and developing a
predictive theory of mass loss for AGB stars, which is a crucial ingredient of
stellar and galactic chemical evolution models.