Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deuterium Fractionation as an Evolutionary Probe in the Infrared Dark
  Cloud G28.34+0.06   We have observed the J=3-2 transition of N2H+ and N2D+ to investigate the
trend of deuterium fractionation with evolutionary stage in three selected
regions in the Infrared Dark Cloud (IRDC) G28.34+0.06 with the Submillimeter
Telescope (SMT) and the Submillimeter Array (SMA). A comprehensible enhancement
of roughly 3 orders of magnitude in deuterium fractionation over the local
interstellar D/H ratio is observed in all sources. In particular, our sample of
massive star-forming cores in G28.34+0.06 shows a moderate decreasing trend
over a factor of 3 in the N(N2D+)/N(N2H+) ratio with evolutionary stage, a
behavior resembling what previously found in low-mass protostellar cores. This
suggests a possible extension for the use of the N(N2D+)/N(N2H+) ratio as an
evolutionary tracer to high-mass protostellar candidates. In the most evolved
core, MM1, the N2H+ (3-2) emission appears to avoid the warm region traced by
dust continuum emission and emission of 13CO sublimated from grain mantles,
indicating an instant release of gas-phase CO. The majority of the N2H+ and
N2D+ emission is associated with extended structures larger than 8" (~ 0.2 pc).

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The categories of this paper are: econ
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The categories of this paper are: mtrl-th
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: stat
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The categories of this paper are: q-alg
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: physics
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The categories of this paper are: plasm-ph
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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: q-bio
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The categories of this paper are: cs