K-BAND SPECTROSCOPY OF OB STARS - A PRELIMINARY CLASSIFICATION

We present 2 mum spectra of 0 and early-B main-sequence stars. These stars show absorption features at Brgamma, 2.113 mum He I, 2.189 mum He II, and emission at 2.116 mum N III, which vary with spectral subtype in a sufficiently ''well behaved'' manner that they can be used as a rough classification system for hot stars. We also show spectra of several O8f, late-0, and early-B giant and supergiant stars. Subtype classification of these stars is also possible, but the luminosity criteria are more subtle. We intend to use our K-band classification system to investigate hot stars embedded in shrouded H II regions to study formation processes and early evolution of the most massive stars. K-band spectra of the Galactic center stars are unlike any of our ''standard'' stars but do appear superficially similar to our spectrum of an Oe star, which has a disklike geometry, although the mechanism for the line formation is probably quite different.