Mass-loss rate versus wind velocity for M-type AGB stars. Observations by Olofsson et al. (2002) and González Delgado et al. (2003) are shown in black (star symbols represent Mira variables, and crosses represent semi-regulars, SRa and SRb); colored symbols represent DARWIN models. Top panel: all models in Table 1 shown, with symbols indicating input parameters. Red symbols mark models of series A and blue symbols models of series B (triangles and diamonds indicate pulsation amplitudes of 3 and 4 km s⁻¹, respectively); models of series M2 are shown as green circles. Bottom panel: selected models, discussed in Sect. 3.3 (see also Table 3). Symbol shapes indicate variability type (same as observations); red symbols represent series A, blue symbols series B, and green symbols series M2.