RGBs in a bolometric luminosity vs. stellar squared radius for models cgm1 to cgm4 of Table 4. The lines conventions are similar as in Fig. 6. The data are the nine giants of group II defined in the text (see also Fig. 3). The data symbols are the same as in Fig. 5: triangle symbols are for objects within 0.04 dex of solar metallicity, triangles for objects within 0.06 dex of  [Fe/H]  = −0.17.