Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 4U 1907+09: a HMXB running away from the Galactic plane   We report the discovery of a bow shock around the high-mass X-ray binary
(HMXB) 4U 1907+09 using the Spitzer Space Telescope 24 $\mu$m data (after Vela
X-1 the second example of bow shocks associated with HMXBs). The detection of
the bow shock implies that 4U 1907+09 is moving through the space with a high
(supersonic) peculiar velocity. To confirm the runaway nature of 4U 1907+09, we
measured its proper motion, which for an adopted distance to the system of 4
kpc corresponds to a peculiar transverse velocity of $\simeq 160 \pm 115$ km/s,
meaning that 4U 1907+09 is indeed a runaway system and supporting the general
belief that most of HMXBs possess high space velocities. The direction of
motion of 4U 1907+09 inferred from the proper motion measurement is consistent
with the orientation of the symmetry axis of the bow shock, and shows that the
HMXB is running away from the Galactic plane. We also present the Spitzer
images of the bow shock around Vela X-1 (a system similar to 4U 1907+09) and
compare it with the bow shock generated by 4U 1907+09.

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The categories of this paper are: chao-dyn
36
The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
2
The categories of this paper are: math
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
35
The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: patt-sol
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom