A comparison of near-infrared spectra of the galactic center compact He I emission-line sources and early-type mass-losing stars
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We present R 570 resolution K band spectra of eight sources in the Galactic center, including four sources within the IRS 16 cluster, IRS 13, IRS 1 W, and the compact He I emission-line sources AF (also known as AHH) and AHH NW. We also present R 570 H and K band spectra of the AF source and nine galactic and LMC early-type mass-losing stars, including Ofpe/WN9, WN, and LBV stars. The spectra of both the Galactic center sources and the comparison stars show a wide range of behavior in the He I (1.70 m, 2.06 m, 2.11 m) and H I (Brackett series) lines. While the Galactic center and comparison star spectra show some morphological similarities, we find significantly larger He I equivalent widths in the AF source and two galactic early-type mass-losing stars than in any of the LMC stars. Several of the Galactic center He I sources are found to have higher He I velocity widths than any of the galactic or LMC early-type mass-losing stars. At least one source, IRS 13, shows significant emission to the red of the He I 2.06 m line emission, which may be a red wing to this line or a blend of other unidentified lines. We also rule the Galactic center He I sources being normal OB giant/supergiants, WC, or WN7-8 stars based on a comparison of our spectra to published spectra of these types. We estimate the BCK = Mbol - MK for the Galactic center sources as a function of effective temperature from published data on LBV, WN9, and Ofpe/WN9 stars, and use limits on the effective temperature to place the Galactic center sources in the H-R diagram.
