Nuclear pasta

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Nuclear pasta ( English nuclear pasta ) is in the astrophysics an exotic state of degenerate matter , wherein the nucleons assume a non-spherical shape. Nuclear pasta got its name from the Italian word for noodles because of its geometric shape, which can be elongated like spaghetti or flat like lasagna .

Forms and Transformation

In non-degenerate matter, the shape of nucleons is spherical . When the density of matter assumes values ​​of 0.2 to 0.5 times the density of protons with values ​​of 0.05 nucleons per femtometer , the value of the electrical repulsion by the Coulomb forces exceeds that of the surface tension due to the strong interaction . This allows the nucleons to take on the following forms:

  • Rod-shaped like spaghetti
  • Plate-shaped like lasagne
  • Rod-shaped cavities in a dense nucleon mass (the anti-spaghetti phase)
  • Spherical cavities in a dense nucleon mass (Swiss cheese)

The shapes transform with increasing density in the order listed above.

Occur

Structure of a neutron star

A nuclear pasta phase could occur in the event of a core collapse during a supernova explosion.

Alternatively, nuclear pasta could also be produced when a neutron star cools down . It should form at the lower edge of the inner crust with a layer thickness of about 100 meters. During this phase, there should be an increased cross-section for neutrinos with an influence on the Urca process .

In pulsars , the nuclear pasta phase should modify the coupling between the inner core with its neutron-proton liquid and the crystalline inner crust. Attempts have been made to demonstrate this in the period jumps of pulsars .

literature

  • G. Röpke: Correlations and Clustering in Dilute Matter . In: WU Schröder (Ed.): Nuclear Particle Correlations and Cluster Physics . World Scientific, 2017, ISBN 981-3209-36-4 , pp. 59 .

See also

Individual evidence

  1. ↑ G. Watanabe, K. Iida, K. Sato: Thermodynamic properties of nuclear "pasta" in neutron star crusts . In: Nuclear Physics A . tape 676 (1-4) , August 2000, ISSN  0375-9474 , p. 455-473 , doi : 10.1016 / S0375-9474 (00) 00197-4 ( sciencedirect.com ).
  2. ↑ FJ Fattoyev, CJ Horowitz, B. Schuetrumpf: Quantum Nuclear Pasta and Nuclear Symmetry Energy . In: Astrophysics. Solar and Stellar Astrophysics . 2017, arxiv : 1703.01433v1 .
  3. ↑ Helmut Hornung: Stars with great attraction . In: MaxPlanckResearch . Max Planck Society, April 2014, ISSN  1616-4172 ( mpg.de [PDF; accessed October 6, 2017]).
  4. ^ ME Caplan, CJ Horowitz: Astromaterial Science and Nuclear Pasta . In: Astrophysics. Solar and Stellar Astrophysics . 2016, arxiv : 1606.03646v2 .
  5. ^ AS Schneider, CJ Horowitz, J. Hughto, DK Berry: Nuclear "pasta" formation . In: Phys. Rev. C . tape 88 , December 2013, doi : 10.1103 / PhysRevC.88.065807 , arxiv : 1307.1678v1 .
  6. ↑ Gentaro Watanabe, Toshiki Maruyama: Nuclear pasta in supernovae and neutron stars . In: Astrophysics. Solar and Stellar Astrophysics . 2011, arxiv : 1109.3511v1 .