Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deuterium enhancement in H3+ in prestellar cores   Deuterium enhancement of monodeuterated species has been recognized for more
than 30 years as a result of the chemical fractionation that results from the
difference in zero point energies of deuterated and hydrogenated molecules. The
key reaction is the deuteron exchange in the reaction between HD, the reservoir
of deuterium in dark interstellar clouds, and the H3+ molecular ion, leading to
the production of the H2D+ molecule, and the low temperature in dark
interstellar clouds favors this production. Furthermore, the presence of
multiply deuterated species have incited our group to proceed further and
consider the subsequent reaction of H2D+ with HD, leading to D2H+ (first
detected by Vastel et al. 2004), which can further react with HD to produce
D3+. In prestellar cores, where CO was found to be depleted (Bacmann et al.
2003), this production should be increased, as CO would normally destroy H3+.
The first model including D2H+ and D3+ (Roberts, Herbst & Millar 2003)
predicted that these molecules should be as abundant as H2D+ (see contribution
by H. Roberts). The first detection of the D2H+ was made possible by the recent
laboratory measurement by Hirao & Amano (2003) for the frequency of the
fundamental line of the para-D2H+ (see contribution by T. Amano). Here we
present observations of H2D+ and D2H+ towards a sample of dark clouds and
prestellar cores and show how the distribution of ortho-H2D+ (1_1,0-1_1,1) can
trace the deuterium factory in prestellar cores. We also present how future
instrumentation will improve our knowledge concerning the deuterium enhancement
of H3+.

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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
5
The categories of this paper are: gr-qc
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The categories of this paper are: ao-sci
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: hep-lat
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The categories of this paper are: nucl-th
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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: alg-geom
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The categories of this paper are: q-alg
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The categories of this paper are: supr-con
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph