1996PASP..108..575G

We present moderate-resolution spectra of normal dwarf O stars taken over the commonly ignored spectral range from 6250 to 7150A. Numerous, strong, telluric absorption features, particularly the prominent O2 feature beyond 6850A, have made the study of stellar photospheres over this spectral region very difficult in the past. In this study, we use a method for removing the atmospheric absorption features during the reduction process. With our cleaned spectra, we have been successful in identifying the He II 6891A line in O dwarf stars that has until now been too heavily contaminated by telluric features to be clearly detected.