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Sirius B, which is a white dwarf, can be seen as a faint point of light to the lower of the much brighter Sirius A. A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: in an Earth sized volume, it packs a mass that is comparable to the Sun.
In white dwarf stars, the positive nuclei are completely ionized – disassociated from the electrons – and closely packed – a million times more dense than the Sun. At this density gravity exerts immense force pulling the nuclei together. This force is balanced by the electron degeneracy pressure keeping the star stable. [4]
In a degenerate gas, all quantum states are filled up to the Fermi energy. Most stars are supported against their own gravitation by normal thermal gas pressure, while in white dwarf stars the supporting force comes from the degeneracy pressure of the electron gas in their interior. In neutron stars, the degenerate particles are neutrons.
White dwarfs are among the most compact objects in the cosmos, though not as dense as a black hole. Stars with up to eight times the mass of our sun appear destined to end up as a white dwarf.
This system permits a test that compares how the gravitational pull of the outer white dwarf affects the pulsar, which has strong self-gravity, and the inner white dwarf. The result shows that the accelerations of the pulsar and its nearby white-dwarf companion differ fractionally by no more than 2.6 × 10 −6 (95% confidence level). [123 ...
The white dwarf cooling anomaly is an additional cooling delay that has been observed for ultramassive forms of these compact stellar remnants. [ 1 ] [ 2 ] As a white dwarf cools, crystallization of the interior releases energy, slowing the cooling rate.
Like other white dwarfs, it is a very dense star: its mass has been estimated to be about 67% of the Sun's, [28] yet it has only 1% of the Sun's radius (1.23 times the Earth's radius). [7] [a] The outer atmosphere has a temperature of approximately 6,110 K, [28] which is relatively cool for a white dwarf. As all white dwarfs steadily radiate ...
The Eskimo Nebula is illuminated by a white dwarf at its center. The stars called white or degenerate dwarfs are made up mainly of degenerate matter; typically carbon and oxygen nuclei in a sea of degenerate electrons. White dwarfs arise from the cores of main-sequence stars and are therefore very hot when