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White dwarfs with hydrogen-poor atmospheres, such as WD J2147–4035, are less affected by CIA and therefore have a yellow to orange color. [80] [77] The white dwarf cooling sequence seen by ESA's Gaia mission. White dwarf core material is a completely ionized plasma – a mixture of nuclei and electrons – that is
The energy released (1– 2 × 10 44 J) [17] is more than sufficient to unbind the star; that is, the individual particles making up the white dwarf gain enough kinetic energy to fly apart from each other.
If many electrons are confined to a small volume, on average the electrons have a large kinetic energy, and a large pressure is exerted. [2] [3]: 32–39 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.
In type Ia white dwarf detonations, most of the energy is directed into heavy element synthesis and the kinetic energy of the ejecta. [174] In core collapse supernovae, the vast majority of the energy is directed into neutrino emission, and while some of this apparently powers the observed destruction, 99%+ of the neutrinos escape the star in ...
Carbon detonation or carbon deflagration is the violent reignition of thermonuclear fusion in a white dwarf star that was previously slowly cooling. It involves a runaway thermonuclear process which spreads through the white dwarf in a matter of seconds, producing a type Ia supernova which releases an immense amount of energy as the star is blown apart.
White dwarfs are luminous not because they are generating energy but rather because they have trapped a large amount of heat which is gradually radiated away. Normal gas exerts higher pressure when it is heated and expands, but the pressure in a degenerate gas does not depend on the temperature.
White dwarfs are no longer generating energy at their cores through nuclear fusion, and instead are steadily radiating away their remaining heat. Gliese 440 has a DQ spectral classification, indicating that it is a rare type of white dwarf which displays evidence of atomic or molecular carbon in its spectrum. [21]
A pulsating white dwarf is a white dwarf star whose luminosity varies due to non-radial gravity wave pulsations within itself. Known types of pulsating white dwarfs include DAV, or ZZ Ceti, stars, with hydrogen-dominated atmospheres and the spectral type DA; [1] DBV, or V777 Her, stars, with helium-dominated atmospheres and the spectral type DB; [2] and GW Vir stars, with atmospheres dominated ...