Degenerate Matter

Highly compressed matter in which the normal atomic structure has broken down and which, because of quantum-mechanical effects, exerts a pressure that is independent of temperature. Bodies with masses <1.4 Msun (e.g., white dwarfs) are supported by electron degeneracy pressure and have densities of ~106 kg/m3. If the mass of a collapsed star >1.4 Msun, gravity will overwhelm electron degeneracy and further collapse ensues. Electrons combine with protons to form neutrons, so producing a neutron star. Because neutrons, like electrons, are subject to the Pauli exclusion principle, at high enough densities ~1014 kg/m3, neutron degeneracy pressure prevents further collapse of the star. For masses >2-3 Msun, even neutron degeneracy can’t prevent further collapse, and a black hole is formed.

Some or all content above used with permission from J. H. Wittke.