The spectral energy distribution (SED) of recent star formation regions is
dominated by the more massive and early stars (O and B types). These stars show
large and very significant absorption features, the most prominent being the
recombination lines of H, HeI and HeII. In particular, the shape of their
profiles are very dependent on the luminosity of the star. We have explored the
potential use of high resolution profiles to discriminate between different
luminosity classes and spectral types, by using profiles of the He and Balmer
lines. We have calculated growth curves for each of the lines and their
dependence on gravity and effective temperature. We show some of these
theoretical growth curves and our preliminary conclusions are analyzed and
discussed.Comment: 1 pag, Contribution to the conference "Cosmic Evolution and Galaxy
Formation: Structure, Interactions and Feedback", Nov. 1999 (Puebla, Mexico),
to be published in ASP. Conf. Series, Eds. J. Franco, E. Terlevich. O.
Lopez-Cruz, I. Aretxag