Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Probing the Crust of the Neutron Star in EXO 0748-676   X-ray observations of quiescent X-ray binaries have the potential to provide
insight into the structure and the composition of neutron stars. EXO 0748-676
had been actively accreting for over 24 yr before its outburst ceased in late
2008. Subsequent X-ray monitoring revealed a gradual decay of the quiescent
thermal emission that can be attributed to cooling of the accretion-heated
neutron star crust. In this work, we report on new Chandra and Swift
observations that extend the quiescent monitoring to ~5 yr post-outburst. We
find that the neutron star temperature remained at ~117 eV between 2009 and
2011, but had decreased to ~110 eV in 2013. This suggests that the crust has
not fully cooled yet, which is supported by the lower temperature of ~95 eV
that was measured ~4 yr prior to the accretion phase in 1980. Comparing the
data to thermal evolution simulations reveals that the apparent lack of cooling
between 2009 and 2011 could possibly be a signature of convection driven by
phase separation of light and heavy nuclei in the outer layers of the neutron
star.

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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
34
The categories of this paper are: chem-ph
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
26
The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
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The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
32
The categories of this paper are: atom-ph
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-ex