AAS 197, January 2001
Session 43. High Mass Star Formation
Display, Tuesday, January 9, 2001, 9:30am-7:00pm, Exhibit Hall

## [43.05] Massive Luminous Stars in the Galactic HII Region W51

A. Leistra, A. Cotera (Steward Observatory), J. Simpson (NASA Ames Research Center)

As part of an ongoing project to identify hot massive stars in highly obscured regions of the Galaxy (see also Simpson, Cotera, and Leistra this meeting), we have used the Steward Observatory Bok 2.3 m telescope with the 256X256 near-infrared camera to obtain broadband H and K band images and with FSPEC to obtain spectra within several regions of the Giant HII Region W51. The areas observed correspond to radio emission peaks within the region. The observations were taken in May-June 2000. Once the broadband images were obtained, areas that contained either diffuse broad band emission or stellar clusters were selected for spectral observation. Spectral scans were taken at R~1000 by fixing the slit in RA and stepping at 1.5'' intervals in Dec across the regions of interest, creating cubes of data with axes \alpha, \delta and \lambda. Candidates for deeper spectra were identified by extracting the Br\gamma (2.166 \mum) and He I (2.058 \mum) emission line images from the data cubes. Emission line images made during similar observations in 1998 were also used to identify candidate objects for higher resolution spectra. At least two candidate hot massive stars in a previously unknown stellar cluster in the G49.4-0.3a component of W51 have been identified. Their spectra contain several He II emission lines in addition to Br\gamma and He I (2.058 & 2.112/3 \mum) lines, which are undoubtably contaminated by nebular emission. The 2.189 \mum line, usually the strongest He II emission line in this spectral region in WR stars, was not observed, but observing He II in O stars is problematic. We will present a preliminary classification of these unusual stars based on their H and K band spectra.