a) The image predicted at the CO band head by the MARCS+MOLsphere model shown in Fig. 3. b) Spatially resolved spectra at the center of the stellar disk (position A in the panel a) and at the edge of the MOLsphere (position B) are shown by the red and blue solid line, respectively. The spatially unresolved spectrum from the MARCS-only model is plotted by the black solid line. The spectrum at the edge of the MOLsphere is scaled up by a factor of 10.