PSR J2144−3933 is a pulsar about 180 parsecs (587 light-years) from Earth.
It is the coldest known neutron star with a surface temperature less than 42000 Kelvin as measured by the Hubble Space Telescope.
It also has the lowest spindown luminosity of any pulsar at about 3×1021 watts.
Writing in Nature, astrophysicists M. D. Young and coworkers consider this object and suggest that its existence throws current theories into doubt.
They state: The fact that J2144−3933 is the coldest observed neutron star has been exploited to constrain the properties of dark matter.