ISF 3.P162-B

X-ray flux from KS 1731-260 after accretion ended,
as measured by repeated Chandra and XMM-Newton observations
over many years. The drop in flux reflects the cooling of
the neutron star crust. This is the first time that the leveling out
of the flux to that presumably from the neutron star core has
been observed. Adapted from [Cac06].

References:
[Cac06] E.M. Cackett et al., arXiv:astro-ph/0605490 (2006)