Evolution of a 4 M_⊙ model star of metallicity Z = 4 × 10⁻³, in terms of the time variation of some physical quantities. Mass loss is modeled according to Blöcker & Schöenberner (1991). Times on the x-axis are zeroed at the beginning of the AGB phase. The left panel shows the variation of luminosity (black line, scale left y-axis) and pulsation period (red, scale on the right). The right panel shows the evolution of the mass-loss rate (black line) and of the stellar radius (red, scale on the right). The green line on the right panel shows the mass-loss rate that would be obtained during the super wind phase if the Vassiliadis & Wood (1993) prescription for mass loss was adopted.