Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exploring the substellar temperature regime down to ~550K   We report the discovery of three very late T dwarfs in the UKIRT Infrared
Deep Sky Survey (UKIDSS) Third Data Release: ULAS J101721.40+011817.9
(ULAS1017), ULAS J123828.51+095351.3 (ULAS1238) and ULAS J133553.45+113005.2
(ULAS1335).We detail optical and near-infrared photometry for all three
sources, and mid-infrared photometry for ULAS1335. We use near-infrared spectra
of each source to assign spectral types T8p (ULAS1017), T8.5 (ULAS1228) and T9
(ULAS1335) to these objects. We estimate that ULAS1017 has 750 < Teff < 850K,
and 5.0 < log g < 5.5, assuming solar metallicity, an age of 1.6-15 Gyr, a mass
of 33-70 MJ and lies at a distance of 31-54 pc. We extend the unified scheme of
Burgasser et al. (2006) to the type T9 and suggest the inclusion of the WJ
index to replace the now saturated J-band indices. ULAS1335 is the same
spectral type as ULAS J003402.77-005206.7 and CFBDS J005910.90-011401.3.
Comparison of model spectra with that of ULAS1335 suggest a temperature below
600K. We find ULAS1335 to be extremely red in near to mid-infrared colours,
with H-[4.49]=4.34+/-0.04. This is the reddest near to mid-infrared colour yet
observed for a T dwarf, which supports Teff < 600K, and we estimate Teff
~550-600K for ULAS1335. We estimate that ULAS1335 has an age of 0.6-5.3 Gyr, a
mass of 15-31 MJ and lies at a distance of 8-12 pc.

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The categories of this paper are: nlin
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: hep-lat
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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: quant-ph
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The categories of this paper are: chao-dyn
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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: q-fin
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The categories of this paper are: hep-ph
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The categories of this paper are: stat
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The categories of this paper are: gr-qc