Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Rapid cooling of magnetized neutron stars   The neutrino emissivities resulting from direct URCA processes in neutron
stars are calculated in a relativistic Dirac-Hartree approach in presence of a
magnetic field. In a quark or a hyperon matter environment, the emissivity due
to nucleon direct URCA processes is suppressed relative to that from pure
nuclear matter. In all the cases studied, the magnetic field enhances
emissivity compared to the field-free cases.

16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
8
The categories of this paper are: hep-ex
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con