SIMBAD references

In order to derive the ratio of α-elements to iron in galaxies, we have observed the strongest TiO band heads of the γ and γ' systems at 7000-7500 Å in a sample of a dozen early-type galaxies. The equivalent widths of the TiO bands are compared with synthetic spectra for single-aged stellar populations and composite galaxy models, all computed with [α/Fe]=0.0 and +0.3. The same method is also applied to the <Fe> and Mg₂ Lick indices for the sample galaxies. The results obtained are [Ti/Fe]~[Mg/Fe]~+0.3, indicating a clear enhancement of the α-elements-to-iron ratio for our sample of early-type galaxies.