NEAR-INFRARED SPECTRA OF COMPACT STELLAR WIND SOURCES AT THE GALACTIC-CENTER

We present high- and low-resolution, H- and K-band spectra of nine com pact 2.2 mu m Galactic center sources in which we clearly detect He I 2.058 mu m emission, including the AF source, IRS 13, IRS 1W, IRS 16NE , IRS 16NW, IRS 16C, IRS 16SW, IRS 34, and IRS 6E. We have also obtain ed comparison spectra of both a luminous blue variable (LBV) and a WR star (P Cygni and HD 192163, respectively). Our H- and K-band spectrum of the LBV P Cygni strongly resembles the near-infrared spectra of kn own WN9/Ofpe stars. Our spectra of the Galactic center sources share m any characteristics in common with our spectrum of P Cygni. The spectr a all show emission lines of H I and He I with large He I/H line flux ratios. Some have permitted and forbidden lines of Fe II. Brackett lin e widths and ratios indicate the presence of strong stellar winds. In contrast to the spectrum of the WR star, none of the Galactic center s ources show evidence of He II emission lines in their spectra, suggest ing that none of the Galactic center sources are WR stars. Our high-re solution H-band spectrum of the AF source differs from previously publ ished low-resolution H-band spectra in that it is rich in emission lin es. Furthermore, we find two distinct spectral components to the AF so urce separated in space by a few arcseconds. We identify both the emis sion-line component of the AF source and an exciting source of IRS 13 as an LBV or WN9/Ofpe star. Our results, when combined with the result s of others, also suggest that IRS 16NE, IRS 16C, IRS 16NW, IRS 34, an d a component of IRS 6E are early-type, emission-line stars. The argum ent for IRS 16SW, however, is less compelling. We find no evidence for a compact He I emission-line source at IRS 1W. This result contradict s previous findings, suggesting that the He I source at IRS 1W may be variable. If the He I lines in IRS 1W are truly variable, a stellar co mponent of IRS 1W may be an LBV, because LBVs are known to have variab le line emission on short timescales. The nine Galactic center wind so urces appear to contribute a significant fraction of the total luminos ity of the central few parsecs of the Galaxy.