Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Molecular Line Observation toward Massive Clumps Associated with
  Infrared Dark Clouds   We have surveyed the N2H+ J=1-0, HC3N J=5-4, CCS J_N=4_3-3_2, NH3 (J, K) =
(1, 1), (2, 2), (3, 3), and CH3OH J=7-6 lines toward the 55 massive clumps
associated with infrared dark clouds by using the Nobeyama Radio Observatory 45
m telescope and the Atacama Submillimeter Telescope Experiment 10 m telescope.
The N2H+, HC3N, and NH3 lines are detected toward most of the objects. On the
other hand, the CCS emission is detected toward none of the objects. The
[CCS]/[N2H+] ratios are found to be mostly lower than unity even in the Spitzer
24 micron dark objects. This suggests that most of the massive clumps are
chemically more evolved than the low-mass starless cores. The CH3OH emission is
detected toward 18 out of 55 objects. All the CH3OH-detected objects are
associated with the Spitzer 24 micron sources, suggesting that star formation
has already started in all the CH3OH-detected objects. The velocity widths of
the CH3OH J_K=7_0-6_0 A+ and 7_{-1}-6_{-1} E lines are broader than those of
N2H+ J=1-0. The CH3OH J_K=7_0-6_0 A+ and 7_{-1}-6_{-1} E lines tend to have
broader linewidth in the MSX dark objects than in the others, the former being
younger or less luminous than the latter. The origin of the broad emission is
discussed in terms of the interaction between an outflow and an ambient cloud.

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The categories of this paper are: funct-an
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: q-bio
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: econ
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The categories of this paper are: math
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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: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph