Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The brightest pure-H ultracool white dwarf   We report the identification of LSR J0745+2627 in the United Kingdom InfraRed
Telescope Infrared Deep Sky Survey (UKIDSS) Large Area Survey (LAS) as a cool
white dwarf with kinematics and age compatible with the thick-disk/halo
population. LSR J0745+2627 has a high proper motion (890 mas/yr) and a high
reduced proper motion value in the J band (H_J=21.87). We show how the
infrared-reduced proper motion diagram is useful for selecting a sample of cool
white dwarfs with low contamination. LSR J0745+2627 is also detected in the
Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer
(WISE). We have spectroscopically confirmed this object as a cool white dwarf
using X-Shooter on the Very Large Telescope. A detailed analysis of its
spectral energy distribution reveals that its atmosphere is compatible with a
pure-H composition model with an effective temperature of 3880+-90 K. This
object is the brightest pure-H ultracool white dwarf (Teff<4000 K) ever
identified. We have constrained the distance (24-45 pc), space velocities and
age considering different surface gravities. The results obtained suggest that
LSR J0745+2627 belongs to the thick-disk/halo population and is also one of the
closest ultracool white dwarfs.

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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: chem-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: funct-an
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The categories of this paper are: q-alg
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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: hep-lat
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph