Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fast Cooling of Neutron Stars: Superfluidity vs. Heating and Accreted
  Envelope   It is generally considered that the neutron star cooling scenarios involving
fast neutrino emission, from a kaon or pion condensate, quark matter, or the
direct Urca process, require the presence of baryon pairing in the central core
of the star to control the strong neutrino emission and produce surface
temperatures compatible with observations. I show here that within the kaon
condensate scenario pairing is not necessary if: 1) the equation of state is
stiff enough for the star to have a thick crust in which sufficient friction
can occur to heat the star and 2) a thin layer, of mass larger than 10^{-12}
Msol, of light elements (H and He) is present at the stellar surface. The
effect of the light elements is to increase the heat flow and thus produce a
higher surface temperature. Both the occurrence of heating and the presence of
H and/or He at the surface (deposited during the late post-supernova accretion)
can possibly be confirmed or infirmed by future observations.

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The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
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The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph