Po-Sheng Ou (ASIAA/NTU); Ke-Jung Chen (ASIAA)
Massive stars can lose large fractions of mass through stellar winds, and these materials can form circumstellar media (CSM). We systematically study stellar mass loss and formation of CSM with stellar evolution models and hydrodynamic simulations. First we use the MESA code to produce a grid of ~2000 stellar models with various initial masses and metallicities. From these models, we calculate the total mass loss and energy feedback during the stellar lifetimes. A critical metallicity of mass loss is found, and this can be explained by the mechanism of red supergiant formation. The mass-loss rates as functions of time from the stellar models are then imported into 2D hydrodynamic simulations. Using these realistic mass-loss rates, we calculate the structures of the CSM produced by stars with different masses and metallicities. We compare the CSM at different stellar evolutionary phases, and the results can be linked with observations. These simulations help us understand feedback from stellar winds, and also circumstellar environments before supernova explosions.