Contribution functions of the thermal emission spectrum calculated using the same parameters as in Fig. B.2. Upper panel: presents the contribution functions over the entire HARPS-N wavelength range and Bottom panel: detailed view in a narrow wavelength range. The contribution functions indicate that the fluxes of the Fe lines are from the upper layer of the temperature inversion, while the continuum flux is from the low altitudes. It appears that we are probing the continuum at the bottom of the atmosphere (which is set as 1 bar), but this result is due to the model setup (i.e. isothermal for pressures larger than P₂). The continuum spectrum is the same if we set the atmospheric lower boundary at P₂ instead of 1 bar.