Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Hubble Space Telescope detection of the double pulsar system J0737-3039
  in the far-ultraviolet   We report on detection of the double pulsar system J0737-3039 in the far-UV
with the ACS/SBC detector aboard HST. We measured the energy flux F =
4.5+/-1.0e-17 erg cm-2s-1 in the 1250-1550 AA band, which corresponds to the
extinction-corrected luminosity L~1.5e28 erg s-1 for the distance d=1.1 kpc and
a plausible reddening E(B-V)=0.1. If the detected emission comes from the
entire surface of one of the neutron stars with a 13 km radius, the surface
blackbody temperature is in the range T~2-5e5 K for a reasonable range of
interstellar extinction. Such a temperature requires an internal heating
mechanism to operate in old neutron stars, or it might be explained by heating
of the surface of the less energetic Pulsar B by the relativistic wind of
Pulsar A. If the far-UV emission is non-thermal (e.g., produced in the
magnetosphere of Pulsar A), its spectrum exhibits a break between the UV and
X-rays.

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The categories of this paper are: gr-qc
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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: hep-lat
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The categories of this paper are: hep-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: q-fin
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The categories of this paper are: atom-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: cond-mat
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The categories of this paper are: eess
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The categories of this paper are: adap-org