page_title: Neutron star
section_title: Population and distances
hierarchical_section_title: Neutron star / Population and distances
caption_attribution_description: English: While many other images of the famous Crab Nebula have focused on the filaments in the outer part of the nebula, this image shows the very heart of the Crab Nebula including the central neutron star — it is the rightmost of the two bright stars near the centre of this image. The rapid motion of the material nearest to the central star is revealed by the subtle rainbow of colours in this time-lapse image, the rainbow effect being due to the movement of material over the time between one image and another.
context_page_description: A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Neutron stars are the smallest and densest stellar objects, excluding black holes and hypothetical white holes, quark stars, and strange stars. Neutron stars have a radius on the order of 10 kilometres and a mass of about 1.4 solar masses. They result from the supernova explosion of a massive star, combined with gravitational collapse, that compresses the core past white dwarf star density to that of atomic nuclei.
  Once formed, they no longer actively generate heat, and cool over time; however, they may still evolve further through collision or accretion. Most of the basic models for these objects imply that neutron stars are composed almost entirely of neutrons; the electrons and protons present in normal matter combine to produce neutrons at the conditions in a neutron star.
context_section_description: At present, there are about 2,000 known neutron stars in the Milky Way and the Magellanic Clouds, the majority of which have been detected as radio pulsars. Neutron stars are mostly concentrated along the disk of the Milky Way, although the spread perpendicular to the disk is large because the supernova explosion process can impart high translational speeds (400 km/s) to the newly formed neutron star.
  Some of the closest known neutron stars are RX J1856.5−3754, which is about 400 light-years from Earth, and PSR J0108−1431 about 424 light years. RX J1856.5-3754 is a member of a close group of neutron stars called The Magnificent Seven. Another nearby neutron star that was detected transiting the backdrop of the constellation Ursa Minor has been nicknamed Calvera by its Canadian and American discoverers, after the villain in the 1960 film The Magnificent Seven. This rapidly moving object was discovered using the ROSAT/Bright Source Catalog.
  Neutron stars are only detectable with modern technology during the earliest stages of their lives (almost always less than 1 million years) and are vastly outnumbered by older neutron stars that would only be detectable through their blackbody radiation and gravitational effects on other stars.
caption: Central neutron star at the heart of the Crab Nebula.[60]
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