BRAINCAKENeutron Stars and Black Holes
If the remnant core left after a supernova has a mass greater than the Chandrasekhar limit (1.44 M☉, where M☉ is one solar mass), electron degeneracy pressure cannot support it, and gravity continues the collapse.
The electrons are forced to combine with protons to form neutrons (releasing neutrinos). The result is a neutron star: a core made almost entirely of neutrons. A neutron star is incredibly dense, similar to the density of an atomic nucleus (of order 1017 kg m−3). A mass of one or two solar masses is packed into a sphere only about 20 km across. It is supported against further collapse by neutron degeneracy pressure. Many neutron stars spin rapidly and are observed as pulsars.
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Key terms in this lesson
- neutron degeneracy pressure
- A quantum pressure arising because neutrons cannot occupy the same quantum state, which supports a neutron star against further gravitational collapse.
- pulsar
- A rapidly rotating neutron star that emits regular pulses of electromagnetic radiation as its beam sweeps past the Earth.
More in Astrophysics and Cosmology
- Formation of a Star
- Evolution of a Low-Mass Star
- Evolution of a Massive Star
- White Dwarfs and the Chandrasekhar Limit
- The Hertzsprung-Russell Diagram
- Energy Levels in Atoms
- Emission and Absorption Line Spectra
- Using Diffraction Gratings to Analyse Starlight
All 24 lessons in Astrophysics and Cosmology · All OCR A-level Physics topics