Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Distribution of Ortho-H_2D+(1_1,0 - 1_1,1) in L1544: Tracing the
  Deuteration Factory in Prestellar Cores   Prestellar cores are unique laboratories for studies of the chemical and
physical conditions preceding star formation. We observed the prestellar core
L1544 in the fundamental transition of ortho-H2D+ (1_1,0-1_1,1) at different
positions over 100", and found a strong correlation between its abundance and
the CO depletion factor. We also present a tentative detection of the
fundamental transition of para-D2H+ (1_1,0-1_0,1) at the dust emission peak.
Maps in N2H+, N2D+, HCO+ and DCO+ are used, and interpreted with the aid of a
spherically symmetric chemical model that predicts the column densities and
abundances of these species as a function of radius. The correlation between
the observed deuterium fractionation of H3+, N2H+ and HCO+ and the observed
integrated CO depletion factor across the core can be reproduced by this
chemical model. In addition a simpler model is used to study the H2D+
ortho-to-para ratio. We conclude that, in order to reproduce the observed
ortho-H2D+ observations, the grain radius should be larger than 0.3 microns.

26
The categories of this paper are: bayes-an
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
27
The categories of this paper are: comp-gas
9
The categories of this paper are: nlin
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con