A state of matter attained when atomic particles are packed together as tightly as is physically possible, at densities of several thousand tonnes per cubic metre. Particles which are very close together are forbidden by the Pauli exclusion principle to have the same energy, and, as a result, the particles repel each other. This causes degeneracy pressure which, unlike thermal pressure, depends only on density and not on temperature. It provides the main support against gravity in white dwarfs (electron degeneracy) and neutron stars (neutron degeneracy). Degenerate matter is found also in the cores of low-mass stars that have exhausted their central hydrogen, in brown dwarfs, and in the central regions of the giant planets.
Subjects: Astronomy and Astrophysics — Chemistry.