Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: SDSS J013655.91+242546.0 - an A-type hyper-velocity star from the
  outskirts of the Galaxy   Hyper-velocity stars (HVS) are moving so fast that they are unbound to the
Galaxy. Dynamical ejection by a supermassive black hole is favoured to explain
their origin. Locating the place of birth of an individual HVS is of utmost
importance to understanding the ejection mechanism. SDSS J013655.91+242546.0
(J0136+2425 for short) was found amongst three high-velocity stars (drawn from
a sample of more than 10000 blue stars), for which proper motions were
measured. A kinematical as well as a quantitative NLTE spectral analysis was
performed. When combined with the radial velocity (RV) and the spectroscopic
distance, the trajectory of the star in the Galactic potential was
reconstructed. J0136+2425 is found to be an A-type main-sequence star
travelling at $\approx$590 \kms, possibly unbound to the Galaxy and originating
in the outer Galactic rim nowhere near the Galactic centre. J0136+2425 is the
second HVS candidate with measured proper motion, besides the massive B star HD
271791, and also the second for which its proper motion excludes a Galactic
centre origin and, hence, the SMBH slingshot mechanism. Most known HVS are late
B-type stars of about 3 M$_\odot$. With a mass of 2.45 M$_\odot$, J0136+2425
resembles a typical HVS far more than HD 271791 does. Hence, this is the first
time that a typical HVS is found not to originate in the Galactic centre. Its
ejection velocity from the disk is so high (550 \kms) that the extreme
supernova binary scenario proposed for HD 271791 is very unlikely.

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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: chem-ph
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The categories of this paper are: funct-an
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: nlin
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The categories of this paper are: cs
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The categories of this paper are: gr-qc
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The categories of this paper are: econ