Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The nature of the dense core population in the Pipe Nebula: A survey of
  NH3, CCS, and HC5N molecular line emission   Recent extinction studies of the Pipe Nebula (d=130 pc) reveal many cores
spanning a range in mass from 0.2 to 20.4 Msun. These dense cores were
identified via their high extinction and comprise a starless population in a
very early stage of development. Here we present a survey of NH3 (1,1), NH3
(2,2), CCS (2_1,1_0), and HC5N (9,8) emission toward 46 of these cores. An
atlas of the 2MASS extinction maps is also presented. In total, we detect 63%
of the cores in NH3 (1,1) 22% in NH3 (2,2), 28% in CCS, and 9% in HC5N
emission. We find the cores are associated with dense gas (~10^4 cm-3) with 9.5
< T_k < 17 K. Compared to C18O, we find the NH3 linewidths are systematically
narrower, implying that the NH3 is tracing the dense component of the gas and
that these cores are relatively quiescent. We find no correlation between core
linewidth and size. The derived properties of the Pipe cores are similar to
cores within other low-mass star-forming regions: the only differences are that
the Pipe cores have weaker NH3 emision and most show no current star formation
as evidenced by the lack of embedded infrared sources. Such weak NH3 emission
could arise due to low column densities and abundances or reduced excitation
due to relatively low core volume densities. Either alternative implies that
the cores are relatively young. Thus, the Pipe cores represent an excellent
sample of dense cores in which to study the initial conditions for star
formation and the earliest stages of core formation and evolution.

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The categories of this paper are: nlin
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ph
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: alg-geom
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The categories of this paper are: stat