Near-IR Spectra of Early-type, Mass-loss Objects

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Session 43 -- Galactic Structure
Display presentation, Wednesday, 9:20-6:30, Pauley Room

[43.01] Near-IR Spectra of Early-type, Mass-loss Objects

S. Libonate, J.L. Pipher, W.J. Forrest (University of Rochester)

There is evidence that the energetics of the Galactic Center may be dominated by a cluster of early-type mass-loss objects rather than by a massive black hole. The exact identification of these sources is unknown, but it has been suggested that they may be WR stars or perhaps objects in some intermediary phase of evolution between O stars and WR stars such as LBV's. In order to classify these sources, we have obtained IR spectroscopy of the central few parsecs of the Galaxy. For comparison we have also obtained spectroscopy of a known luminous blue variable and of two WR stars using the same instrument.

In this paper we present the near-IR spectrum of an object located a few arcseconds west of Galactic Center source IRS 12 known as the AF source. The AF source is a strong WR/LBV candidate because of its anomalous Helium to Hydrogen ratio and broad emission lines which are indicative of a strong stellar wind. We also present the spectra of the luminous blue variable P Cygni, a WN6 star (HD192163), and a WC8 star (HD192103). For P Cygni and the AF source, spectra were obtained in the H and K infrared bands at a resolution of approximately 250, and in the 2.1 to 2.2 micron region at a resolution of about 1500. For the WN6 star, only the low resolution H and K band spectra were obtained, while for the WC8 star only high resolution data were obtained. The line ratios and widths are used to infer the nature of the line-emitting region for each of the three types of sources. We then speculate on the evolutionary phase of the AF source, and discuss the implications for the energetics of the Galactic Center.

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