Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A search for planetary-mass objects and brown dwarfs in the Upper
  Scorpius association   We report the results of a deep photometric search for planets and brown
dwarfs in the nearby young OB Upper Scorpius association. We obtained optical
(I) and near-infrared (JKs) images around nine very low-mass stars and brown
dwarf member candidates of the association, covering a total area of 113
arcmin^2. Using a point spread function subtraction technique, we have searched
for planetary-mass companions (0.002 Msol < M < 0.013 Msol) at separations as
close as 3 arcsec from the targets. We have not found any brown dwarfs more
massive than 0.030 Msol at projected distances larger than 70AU, or planets
more massive than 0.007 Msol at projected distances larger than 600AU. We set
an upper limit of 20% (confidence level 68.3%) to the fraction of very low-mass
stars and massive brown dwarfs with planetary mass companions (M > 0.007 Msol)
at physical distances larger than 600AU. From the I, I-J colour-magnitude
diagrams and follow-up Ks-band photometry, we identify four very red objects
(I-J > 2.5) in the area of the survey. According to their positions in the
diagram, below the expected theoretical sequence of the cluster, three are
probable late M-dwarfs in the field. The faintest and reddest object (J-Ks =
2.39 +/- 0.06) may be either a field intermediate L-dwarf with anomalously red
J-Ks colour at a distance of approx. 135pc, an extremely red distant galaxy, or
a reddened planetary-mass object in the Upper Scorpius association.

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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: q-bio
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: physics
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: q-fin