Fig. 3. Final spectra for the 11 stars observed. The spectra are ordered from earlier to later spectral types (see Sect. 3.2) and correspond, from top to bottom, to the following objects (indicated in parentheses): #5, #8, #4, #12, #11, #10, #1a, #2b, #3, #2a and #7. Blue and red spectra overlap smoothly in the 5400 Å region (indicated by an arrow), with the exception of the star #1a for which the blue and red spectra shown correspond to different phases.