"Explaining the winds of asymptotic giant branch stars: Recent progress"
Evolved stars and their winds play a crucial role for galactic chemical evolution, including the origin of building blocks for planets and life. Essential chemical elements, like carbon, are produced inside these stars, transported to the surface by turbulent gas flows, and ejected into interstellar space by massive outflows of gas and dust. The winds observed around asymptotic giant branch stars are generally attributed to radiation pressure on dust, which is formed in the extended dynamical atmospheres of these pulsating, strongly convective stars. Current radiation-hydrodynamical models can explain many of the observed features, and are on the brink of delivering a predictive theory of mass loss. I will present an overview of recent results and ongoing work on winds of AGB stars, discussing critical ingredients of the driving mechanism. In particular, I will describe our latest global 3D RHD star-and-wind-in-a-box simulations. With such models it becomes possible to follow the flow of matter, in full 3D geometry, all the way from the turbulent, pulsating interior of an AGB star, through its atmosphere and dust formation zone into the region where the wind is accelerated by radiation pressure on dust. Advanced instruments, which can resolve the stellar atmospheres, where the winds originate, provide essential data for testing the models.