Effect of the depletion of oxygen to enhance the C/O ratio on the integrated line flux of CO (4.936–5.298 µm), H₂O (4.891–18.474 µm), and C₂H₂ (11.664–17.289 µm). The black horizontal line shows the CO observed integrated flux, with the grey area indicating the error. The blue shaded area shows the H₂O upper limit, and the brown line and shaded area show the integrated observed flux of C₂H₂ and its associated error. The C₂H₂ flux for the model with a C/O ratio of 0.45 was low (∼6×10⁻¹⁹ Wm⁻²) and is therefore not shown. The dotted vertical line highlights the model with a typical C/O ratio of 0.45.