SIMBAD references

Synthetic spectra of single-aged old stellar populations of metallicities in the range -1.0≤[Fe/H]≤+0.3 are computed in the spectral region 6950-7550A containing TiO bands, by combining synthetic spectra of individual stars. The moderately metal-poor composite spectra are based on isochrones for all evolutionary sequences, whereas the metal-rich ones are based on isochrones for the main sequence and on observed colour-magnitude diagrams for the evolved stages. The composite synthetic spectra are compared to integrated spectra of Galactic globular clusters and good agreement is found. From the resulting single-aged grid we derive relations between equivalent width W(TiO) versus metallicity and [α-elements/Fe].