Po-Sheng Ou (ASIAA/NTU); Ke-Jung Chen (ASIAA)
Stellar winds inject mass and energy into the interstellar medium, playing an important role in stellar feedback. Mass loss of progenitor stars also affects their supernova types. However, the amount of mass lost and energy released during stellar evolution are highly uncertain. Especially, for low-metallicity stars in the early and local universe, while mass loss is thought to be weak, its role is still unknown. To investigate mass loss quantitatively, we include wind recipes based on empirical laws in the MESA code and perform 1D simulations of stellar evolution. We use a grid of initial masses and metallcities in our simulations, and systematically study their effects on mass loss. Our results show a critical metallicity Zc~0.001 as a transition of mass loss. At the Z<0.001 regime, very little fractions of stellar masses are lost. When Z>0.001, the fractions of mass lost become large, and remain similar at different Z>Zc. Whether the stars can successfully evolve to the red supergiant phase is the crucial reason that makes such a difference in mass loss. Nevertheless, the boundary of the two regimes is not well defined, as large variations in mass loss exist near Zc through different masses. Furthermore, we calculate the kinetic energy released by stellar winds. The mass loss histories from our 1D MESA models can be used to build up as realistic initial conditions for 2D and 3D simulations of stellar winds in the future.