Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absolute Nuv magnitudes of Gaia DR1 astrometric stars and a search for
  hot companions in nearby systems   Accurate parallaxes from Gaia DR1 (TGAS) are combined with GALEX visual Nuv
magnitudes to produce absolute Mnuv magnitudes and an ultraviolet HR diagram
for a large sample of astrometric stars. A functional fit is derived of the
lower envelope main sequence of the nearest 1403 stars (distance < 40 pc),
which should be reddening-free. Using this empirical fit, 50 nearby stars are
selected with significant Nuv excess. These are predominantly late K and early
M dwarfs, often associated with X-ray sources, and showing other manifestations
of magnetic activity. The sample may include systems with hidden white dwarfs,
stars younger than the Pleiades, or, most likely, tight interacting binaries of
the BY Dra-type. A separate collection of 40 stars with precise trigonometric
parallaxes and Nuv - G colors bluer than 2 mag is presented. It includes
several known novae, white dwarfs, and binaries with hot subdwarf (sdOB)
components, but most remain unexplored.

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The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
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The categories of this paper are: q-alg
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
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The categories of this paper are: plasm-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom