Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2 micron Spectroscopy within 0.3 arcseconds of SgrA*   We present moderate (R~$\approx$~2,700) and high resolution
(R~$\approx$~22,000) 2.0$-$2.4 \micron\ spectroscopy of the central 0.1 square
arcseconds of the Galaxy obtained with NIRSPEC, the facility near-infrared
spectrometer for the Keck II telescope. The composite spectra do not have any
features attributable to the brightest stars in the central cluster, i.e.\
after background subtraction, W$_{\rm ^{12}CO(2-0)}$~$<$~2~\AA. This stringent
limit leads us to conclude that the majority, if not all, of the stars are
hotter than typical red giants. Coupled with previously reported photometry, we
conclude that the sources are likely OB main sequence stars. In addition, the
continuum slope in the composite spectrum is bluer than that of a red giant and
is similar to that of the nearby hot star, IRS16NW. It is unlikely that they
are late-type giants stripped of their outer envelopes because such sources
would be much fainter than those observed. Given their inferred youth
($\tau_{\rm age}$~$<$~20~\Myr), we suggest the possibility that the stars have
formed within 0.1 pc of the supermassive black hole. We find a newly-identified
broad-line component (V$_{\rm FWHM}$ $\approx$ 1,000 \kms) to the 2.2178
\micron\ [\ion{Fe}{3}] line located within a few arcseconds of Sgr~A$^*$. A
similar component is not seen in the Br-$\gamma$ emission.

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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: cs
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The categories of this paper are: atom-ph
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: supr-con
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The categories of this paper are: physics
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The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga