Synthetic emission spectra as in Fig. 5, but with constant C/O ratio of 0.46. The oxygen abundance here is scaled with metallicity. The blue and pink curves represent cases with solar metallicity. The respective black-body emission is represented as thin curves in the same colour. Major contributing opacities for solar cases are indicated with shaded regions. The inset shows the corresponding temperature profiles. The surface temperature increases with metallicity, shifting temperature-pressure profiles to the right. Spectra are shown at a resolution of λ/∆λ = 600.