RADEX predictions for the SiO (5–4)/(2–l) integrated intensity ratio plotted as a function of the thermal pressure, n(H₂)T, for two different line widths 13 km s⁻¹ (top) and 30 km s⁻¹ (bottom). The calculations were carried out for SiO column density of 10¹³ cm⁻² and kinetic temperatures of 25, 50, 100 and 250 K. The observed range of line ratios for the narrow components (represented by blue dashed lines) and broad components (represented by red dashed lines) are also plotted.