Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gas physical conditions and kinematics of the giant outflow Ou4   Ou4 is a recently discovered bipolar outflow with a projected size of more
than one degree in the plane of the sky. It is apparently centred on the young
stellar cluster -whose most massive representative is the triple system HR8119-
inside the HII region Sh 2-129. The driving source, the nature, and the
distance of Ou4 are not known. Deep narrow-band imagery of the whole nebula at
arcsec resolution was obtained to study its morphology. Long-slit spectroscopy
of the tips of the bipolar lobes was secured to determine the gas ionization
mechanism, physical conditions, and line-of-sight velocities. An estimate of
the proper motions at the tip of the south lobe using archival images is
attempted. The existing multi-wavelength data for Sh 2-129 and HR 8119 are also
comprehensively reviewed. The morphology of Ou4, its emission-line spatial
distribution, line flux ratios, and the kinematic modelling adopting a
bow-shock parabolic geometry, illustrate the expansion of a shock-excited fast
collimated outflow. The radial velocities and reddening are consistent with
those of Sh 2-129 and HR 8119. The improved determination of the distance to
HR8119 (composed of two B0 V and one B0.5 V stars) and Sh 2-129 is 712 pc. We
identify in WISE images a 5 arcmin-radius (1 pc at the distance above) bubble
of emission at 22 micron emitted by hot (107 K) dust, located inside the
central part of Ou4 and corresponding to several [O III] features of Ou4. The
apparent position and the properties studied in this work are consistent with
the hypothesis that Ou4 is located inside the Sh 2-129 HII region, suggesting
that it was launched some 90 000 yrs ago by HR8119. The outflow total kinetic
energy is estimated to be ~4e47~ergs. However, the alternate possibility that
Ou4 is a bipolar planetary nebula, or the result of an eruptive event on a
massive AGB or post-AGB star not yet identified, cannot be ruled out.

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The categories of this paper are: math
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: cs
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: gr-qc
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: comp-gas