Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Nitrogen hydrides in interstellar gas: Herschel/HIFI observations
  towards G10.6-0.4 (W31C)   The HIFI instrument on board the Herschel Space Observatory has been used to
observe interstellar nitrogen hydrides along the sight-line towards G10.6-0.4
in order to improve our understanding of the interstellar chemistry of
nitrogen. We report observations of absorption in NH N=1-0, J=2-1 and ortho-NH2
1_1,1-0_0,0. We also observed ortho-NH3 1_0-0_0, and 2_0-1_0, para-NH3 2_1-1_1,
and searched unsuccessfully for NH+. All detections show emission and
absorption associated directly with the hot-core source itself as well as
absorption by foreground material over a wide range of velocities. All spectra
show similar, non-saturated, absorption features, which we attribute to diffuse
molecular gas. Total column densities over the velocity range 11-54 km/s are
estimated. The similar profiles suggest fairly uniform abundances relative to
hydrogen, approximately 6*10^-9, 3*10^-9, and 3*10^-9 for NH, NH2, and NH3,
respectively. These abundances are discussed with reference to models of
gas-phase and surface chemistry.

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The categories of this paper are: cs
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The categories of this paper are: math-ph
29
The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
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The categories of this paper are: math
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: stat
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The categories of this paper are: atom-ph
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The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex