Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Spatial Separation of the 3.29 micron Emission Feature and Associated 2
  micron Continuum in NGC 7023   We present a new 0.9" resolution 3.29 micron narrowband image of the
reflection nebula NGC 7023. We find that the 3.29 micron IEF in NGC 7023 is
brightest in narrow filaments NW of the illuminating star. These filaments have
been seen in images of K', molecular hydrogen emission lines, the 6.2 and 11.3
micron IEFs, and HCO+. We also detect 3.29 micron emission faintly but
distinctly between the filaments and the star. The 3.29 micron image is in
contrast to narrowband images at 2.09, 2.14, and 2.18 micron, which show an
extended emission peak midway between the filaments and the star, and much
fainter emission near the filaments. The [2.18]-[3.29] color shows a wide
variation, ranging from 3.4-3.6 mag at the 2 micron continuum peak to 5.5 mag
in the filaments. We observe [2.18]-[3.29] to increase smoothly with increasing
distance from the star, up until the filament, suggesting that the main
difference between the spatial distributions of the 2 micron continuum and the
the 3.29 micron emission is related to the incident stellar flux. Our result
suggests that the 3.29 micron IEF carriers are likely to be distinct from, but
related to, the 2 micron continuum emitters. Our finding also imply that, in
NGC 7023, the 2 micron continuum emitters are mainly associated with HI, while
the 3.29 micron IEF carriers are primarily found in warm molecular hydrogen,
but that both can survive in HI or molecular hydrogen. (abridged)

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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: math
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: math-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cond-mat