Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Shock excited far-infrared molecular emission around T Tau   The first complete far-infrared spectrum of T Tau has been obtained with the
LWS spectrometer on-board the Infrared Space Observatory, which detected strong
emission from high-J (J=14-25) CO, para- and ortho-H2O and OH transitions over
the wavelength range from 40 to 190 micron. Most of the observed molecular
emission can be explained by a single emission region at T~300-900 K and
n(H_2)~10^(5-6) cm^(-3),with a diameter of about 2-3 arcsec. This corresponds
to a very compact region of 300-400 AU at the distance of 140 pc. An higher
temperature component seems to be needed to explain the highest excitation CO
and water lines. We derive a water abundance of 1-7x10^(-5) and an OH abundance
of ~3x10^(-5) with respect to molecular hydrogen, implying water and OH
enhancements by more than a factor of 10 with respect to the expected ambient
gas abundance. The observed cooling in the various species amounts to 0.04
L(sun),comparable to the mechanical luminosity of the outflow, indicating that
the stellar winds could be responsible of the line excitation through shocks.
In order to explain the observed molecular cooling in T Tau in terms of C-type
shock models, we hypothesise that the strong far-ultraviolet radiation field
photodissociates water in favour of OH. This would explain the large
overabundance of OH observed. The estimated relatively high density and
compactness of the observed emission suggest that it originates from the shocks
taking place at the base of the molecular outflow emission, in the region where
the action of the stellar winds from the two stars of the binary system is
important.

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The categories of this paper are: atom-ph
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
11
The categories of this paper are: hep-lat
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
8
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: chao-dyn
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The categories of this paper are: nucl-ex
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The categories of this paper are: physics