Cosmic Mysteries Codexery

Neutron stars

Gravitationally collapsed cores of massive stars, second only to black holes.

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Neutron stars are the collapsed cores of massive supergiant stars, formed during a supernova explosion that compresses the core to atomic-nucleus density.[1] They are the second-smallest and second-densest known stellar objects, with a radius of about 10 km and a mass around 1.4 solar masses.[1]

Key facts and history

Any main-sequence star with an initial mass greater than 8 solar masses can potentially become a neutron star.[2] Further mass deposits cause the core to exceed the Chandrasekhar limit, overcoming electron-degeneracy pressure and triggering collapse.[2] The neutron star retains most of its parent's angular momentum, resulting in very high rotation speeds that slow over long periods.[3] During stellar evolution, nucleosynthesis creates a core rich in iron.[2]

Once the core's nuclear fuel is depleted, degeneracy pressure alone provides its support.[2] Simultaneously, electrons and protons merge via electron capture to create neutrons.[2] Observed neutron stars spin with periods ranging from roughly 1.4 milliseconds up to 30 seconds.[3] PSR J0952–0607, the heaviest neutron star yet found, has an estimated mass of 2.35 solar masses.[4]

What the cited sources add

The same source explains that researchers found evidence for a carbon atmosphere only about 4 inches thick on the neutron star in Cassiopeia A, compressed by surface gravity 100 billion times stronger than Earth's.[5] Duncan's magnetar article states that magnetar interior fields may range up to 10^16 Gauss, with some field lines wrapped in a toroidal geometry inside the star.[6] The Chandra Q&A states that a neutron star is born very hot and gradually cools, with a surface temperature of about 1 million Kelvin for a 1 thousand to 1 million year old star.[7] The Space.com article reports that JWST and Hubble observations confirmed neutron star mergers forge elements heavier than gold, including through the r-process.[8]

According to a ChandraBlog entry from 2013, a cricket ball composed of neutron-star material would have a mass of about 20 trillion kg, and neutron stars produce magnetic fields up to a quadrillion times stronger than Earth's.[5]

References

  1. Wikipedia, "Neutron star" (CC BY-SA 4.0), which cites: Glendenning, "Compact Stars: Nuclear Physics, Particle Physics and General Relativity", Springer Science & Business Media, 2012, p. 1; Seeds, "Astronomy: The Solar System and Beyond", Cengage Learning, 2009, p. 339; Heger, "How Massive Single Stars End Their Life", Astrophysical Journal, 2003, p. 288–300 (we also read that source) en.wikipedia.org
  2. Wikipedia, "Neutron star" (CC BY-SA 4.0), which cites: Bombaci, "The Maximum Mass of a Neutron Star", Astronomy and Astrophysics, 1996, p. 871–877 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Neutron star" (CC BY-SA 4.0), which cites: Haensel, "Neutron Stars", Springer, 2007; "The Remarkable Properties of Neutron Stars - Fresh Chandra News", ChandraBlog, 2013-03-28; "The Remarkable Properties of Neutron Stars - Fresh Chandra News", ChandraBlog, 2013-03-28 (we also read that source) en.wikipedia.org
  4. Wikipedia, "Neutron star" (CC BY-SA 4.0), which cites: Croswell, "The heaviest neutron star on record is 2.35 times the mass of the sun", Science News, 2022-07-22 (original not read by us) en.wikipedia.org
  5. "The Remarkable Properties of Neutron Stars - Fresh Chandra News", ChandraBlog, 2013-03-28. facts only, no text reused. chandra.harvard.edu
  6. Duncan, "'Magnetars', soft gamma repeaters & very strong magnetic fields", March 2003. facts only, no text reused. solomon.as.utexas.edu
  7. "Q&A: Supernova Remnants and Neutron Stars", Chandra.harvard.edu (September 5, 2008). facts only, no text reused. Chandra.harvard.edu
  8. Lea, "James Webb Space Telescope finds neutron star mergers forge gold in the cosmos: 'It was thrilling'", Space.com, 21 February 2024. facts only, no text reused. space.com

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Neutron star (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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