Evolutionary synthesis of the stellar population in elliptical galaxies. III. Detailed optical spectra

The evolutionary synthesis technique is used to construct population models for giant elliptical galaxies, using detailed spectrophotometric data for the galaxies and for stars obtained with the Oke multichannel spectrometer on the Hale telescope. We find that ellipticals are well represented by an old metal-rich population with a turnoff at B-Vapprox.0.80 and a turnoff mass function slope x< or approx. =1, plus a quite significant contribution from stars above the turnoff. The nature of these objects is discussed, and it is concluded that the present data and astrophysical constraints cannot distinguish between a small young population and a blue straggler population augmented by a few O stars