Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A PDR model for the FIR mid-$J$ CO ladder with universal rotational
  temperature in star forming region   A photon dominated region (PDR) is one of the leading candidate mechanisms
for the origin of the warm CO gas with near universal $\sim$300~K rotational
temperature inferred from the CO emission detected towards embedded protostars
by Herschel/PACS. We have developed a PDR model in general coordinates, where
we can use the most adequate coordinate system for an embedded protostar having
outflow cavity walls, to solve chemistry and gas energetics self-consistently
for given UV radiation fields with different spectral shapes. Simple 1D tests
and applications show that FIR mid-$J$ ($14\leq J\leq 24$) CO lines are emitted
from near the surface of a dense region exposed to high UV fluxes. We apply our
model to HH46 and find the UV-heated outflow cavity wall can reproduce the
mid-$J$, CO transitions observed by Herschel/PACS. A model with UV radiation
corresponding to a blackbody of 10,000~K results in the rotational temperature
lower than 300~K, while models with the Draine interstellar radiation field and
the 15,000 K blackbody radiation field predict the rotational temperature
similar to the observed one.

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The categories of this paper are: gr-qc
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
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The categories of this paper are: econ
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom