Similar to Fig. 16, except that the radius of the pseudo-continuum in the model, R_continuum, is changed to 3.65 × 10¹³ cm for model 250420 (left column) and 3.85 × 10¹³ cm for model 291820 (right column). The modelled continuum levels are therefore slightly higher than those adopting R_continuum = 3.60 × 10¹³ cm. The strong shock fronts predicted in these two models are hidden inside the radio continuum. The middle and bottom rows show the selected resultant SiO spectra from the corresponding models.