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While degeneracy pressure usually dominates at extremely high densities, it is the ratio between degenerate pressure and thermal pressure which determines degeneracy. Given a sufficiently drastic increase in temperature (such as during a red giant star's helium flash ), matter can become non-degenerate without reducing its density.
Using the Fermi gas as a model, it is possible to calculate the Chandrasekhar limit, i.e. the maximum mass any star may acquire (without significant thermally generated pressure) before collapsing into a black hole or a neutron star. The latter, is a star mainly composed of neutrons, where the collapse is also avoided by neutron degeneracy ...
In the nonrelativistic case, electron degeneracy pressure gives rise to an equation of state of the form P = K 1 ρ 5/3, where P is the pressure, ρ is the mass density, and K 1 is a constant. Solving the hydrostatic equation leads to a model white dwarf that is a polytrope of index 3 / 2 – and therefore has radius inversely ...
This is the pressure that prevents a white dwarf star from collapsing. A star exceeding this limit and without significant thermally generated pressure will continue to collapse to form either a neutron star or black hole, because the degeneracy pressure provided by the electrons is weaker than the inward pull of gravity.
Astronomy provides a spectacular demonstration of the effect of the Pauli principle, in the form of white dwarf and neutron stars. In both bodies, the atomic structure is disrupted by extreme pressure, but the stars are held in hydrostatic equilibrium by degeneracy pressure, also known as Fermi pressure.
They therefore provide neutron degeneracy pressure to support a neutron star against collapse. In addition, repulsive neutron-neutron interactions [ citation needed ] provide additional pressure. Like the Chandrasekhar limit for white dwarfs, there is a limiting mass for neutron stars: the Tolman–Oppenheimer–Volkoff limit , where these ...
Photosynthesis usually refers to oxygenic photosynthesis, a process that produces oxygen. Photosynthetic organisms store the chemical energy so produced within intracellular organic compounds (compounds containing carbon) like sugars, glycogen , cellulose and starches .
The above processes reduce the core energy and its lepton density. Hence, the electron degeneracy pressure is unable to stabilize the stellar core against the gravitational force, and the star collapses. [15] When the density of the central region of collapse exceeds 10 12 g/cm 3, the diffusion time of neutrinos exceeds the collapse time ...