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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
An intermediate-mass binary pulsar (IMBP) is a pulsar-white dwarf binary system with a relatively long spin period of around 10–200 ms consisting of a white dwarf with a relatively high mass of approximately . [7] The spin periods, magnetic field strengths, and orbital eccentricities of IMBPs are significantly larger than those of low mass binary pulsars (LMBPs). [7]
The influx of matter on the white dwarf's surface causes periodic thermonuclear explosions to occur. The usual apparent magnitude of this star system is 15.5, but there have been observed eruptions with maximal apparent magnitude of about 7.0 in the years 1890, 1902, 1920, 1944, 1966 and 2011. [ 6 ]
SDSS 1557 (SDSS J155720.77+091624.6, WD 1554+094) is a binary system composed of a white dwarf and a brown dwarf.The system is surrounded by a circumbinary debris disk.The debris disk was formed when a minor planet was tidally disrupted around the white dwarf in the past.
About 6% of white dwarfs show infrared excess due to a disk around a white dwarf. [66] In the past only a relative small sample of white dwarf disks was known. [67] Due to advances in white dwarf detection (e.g. with Gaia or LAMOST) and improvement of WISE infrared catalogs with unWISE/CatWISE, the number has increased to hundreds of candidates.
Fowler described white dwarfs as composed of a gas of particles that became degenerate at low temperature; he also pointed out that ordinary atoms are broadly similar in regards to the filling of energy levels by fermions. [3] Milne proposed that degenerate matter is found in most of the nuclei of stars, not only in compact stars. [4]
The model developed to explain the observations was that AM Canum Venaticorum is a binary system consisting of a pair of white dwarfs in a close orbit. The primary is a more massive white dwarf composed of carbon / oxygen , whereas the secondary is a less massive white dwarf made of helium , with no hydrogen but traces of heavier elements. [ 2 ]
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 ...