The massive outflows of evolved stars - highly enriched in dust and heavy elements - not only play a central role in the chemical evolution of galaxies, but also provide the raw material for planetary systems and life. The origin of these outflows is still poorly understood, however, the recent tremendous progress in computational facilities, together with spatially resolved, multi-wavelength and increasingly multi-epoch observations, presents a perfect opportunity to test our theories and improve our understanding of mass loss from stars in their final phases of evolution.
Our high-resolution ALMA observations of cool, evolved giant stars have revealed complex and intricate structures in their extended circumstellar envelopes, e.g., spirals, shells, cavities, arcs, jets and disks; fossil records of their stellar mass-loss histories which also hold important clues to the physical processes driving their outflows. Using front-line numerical codes that include realistic treatments of the important microphysics, hydrodynamic and radiative processes, we model these cool giants in 3D, tracing their outflows from their stellar surfaces to the interstellar medium. In this talk, I will focus on our studies of the impact of interactions with a nearby companion, and their role in driving and shaping the complex and in some cases, explosive outflows. I will also discuss the progress we have made towards validating our new mode of binary interaction, wind Roche-lobe overflow, and discuss its implications for symbiotic binaries and related systems such as chemically peculiar stars, X-ray binaries and the progenitors of Type Ia supernovae.