Comparison between the Pollux model computed with the parameters obtained from spectroscopy (red line) and the observed spectrum of Valdes et al. (2004) (left panel)/the SED of Alekseeva et al. (1997) (right panel). The model was degraded to the resolution of the observed spectra (R ∼ 10 000 in the left panel, R ∼ 100 in the right panel). In addition, the model and the observed spectrum of the left panel were smoothed for clarity of the comparison. In both panels the spectra have been normalized with respect to their flux at 5500 Å. The dot-dashed line shows the UBVRI filters throughputs. The bottom panels show the difference between model and observation.