Stars on the Asymptotic Giant Branch

• Around 1 M_Sun, T_eff around/below 3000 K, gravity can be low
• carbon to oxygen ratio can be > 1 (unlike Sun)

• wind: 10^-5 .. 10^-4 M_Sun/yr

Dust formation: Theory

• Dust formation
  • needs large densities so that atoms/molecules collide often enough
  • needs low temperatures so that atoms/molecules keep sticking together
  • does not work in a hydrostatic atmosphere
  • can be modelled by 1D hydrodynamic simulations (piston models)