Speaker
Description
The heavy mass-loss experienced by evolved asymptotic giant branch (AGB) stars provides metals and dust to the interstellar medium (ISM) from which new stars and planets will form. In our current understanding, mass loss occurs through dust-driven winds originating from the extended atmospheres of these stars. When the material has reached the cooler regions so that sufficient dust can form, radiation pressure accelerates the dust which drags the gas along the elements processed are injected in the AGB star are injected into the ISM. However, our understanding of the extended atmospheres of AGB stars is still poor. State-of-the-art simulations show that large convective cells play an important role, but recent observations at milliarcsecond resolution with ALMA have shown that the conditions in the extended atmospheres might be different than predicted by the models. Low-frequency Square Kilometer Array observations of evolved stars will make it possible to study the critical outer regions of the extended atmospheres where dust forms and is accelerated. With the high resolution and sensitivity of SKA, we can constrain atmospheric density and temperature structures at larger distances from the star. Also, simultaneous observations of SKA and ALMA will produce wide-range multi-wavelength data for various radii of the extended atmosphere, enabling us to test and constrain theoretical models in a way that was not possible before. With the fixed configuration and large field of view of SKA, we can study the temporal evolution of evolved star atmospheres and dust-forming regions. In this presentation, we will present these opportunities for the SKA to contribute in this field.
