Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Chemical and radiative transfer modeling of the ISO-LWS Fabry-Perot
  spectra of Orion-KL water lines   We present chemical and radiative transfer models for the many far-IR ortho-
and para-H2O lines that were observed from the Orion-KL region in high
resolution Fabry-Perot (FP) mode by the Long Wavelength Spectrometer (LWS) on
board the Infrared Space Observatory (ISO). The chemistry of the region was
first studied by simulating the conditions in the different known components of
Orion-KL: chemical models for a hot core, a plateau and a ridge were coupled
with an accelerated Lambda$-iteration (ALI) radiative transfer model to predict
H2O line fluxes and profiles. Our models include the first 45 energy levels of
ortho- and para-H2O. We find that lines arising from energy levels below 560 K
were best reproduced by a gas of density 3x10^5 cm^-3 at a temperature of 70-90
K, expanding at a velocity of 30 km s^-1 and with a H2O/H2 abundance ratio of
the order of 2 - 3 x 10^-5, similar to the abundance derived by Cernicharo et
al. (2006). However, the model that best reproduces the fluxes and profiles of
H2O lines arising from energy levels above 560 K has a significantly higher
H2O/H2 abundance, 1 - 5 x 10^-4, originating from gas of similar density, in
the Plateau region, that has been heated to 300 K, relaxing to 90-100 K. We
conclude that the observed water lines do not originate from high temperature
shocks.

2
The categories of this paper are: math
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph