Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chemistry in Disks. IX. Observations and modeling of HCO+ and DCO+ in DM
  Tau   We present resolved Plateau de Bure Array observations of DM Tau in lines of
HCO+ (3-2), (1-0) and DCO+ (3-2). A power-law fitting approach allowed a
derivation of column densities of these two molecules. A chemical inner hole of
~50 AU was found in both HCO+ and DCO+ with DCO+ emission extending to only 450
AU. An isotopic ratio of R_D = N(DCO+) / N(HCO+) was found to range from 0.1 at
50 AU and 0.2 at 450 AU. Chemical modeling allowed an exploration of the
sensitivity of these molecular abundances to physical parameters out with
temperature, finding that X-rays were the domination ionization source in the
HCO+ molecular region and that R_D also is sensitive to the CO depletion. The
ionization fraction, assuming a steady state system, was found to be x(e-) ~
10$^{-7}$. Modeling suggests that HCO+ is the dominant charged molecule in the
disk but its contribution to ionization fraction is dwarfed by atmoic ions such
as C+, S+ and H+.

32
The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
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The categories of this paper are: dg-ga
4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: eess
16
The categories of this paper are: stat
3
The categories of this paper are: physics
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an