White dwarf - Knowledge

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Cambridge, and I discussed. This piece of apparently routine work proved very fruitful – it led to the discovery that all the stars of very faint absolute magnitude were of spectral class M. In conversation on this subject (as I recall it), I asked Pickering about certain other faint stars, not on my list, mentioning in particular 40 Eridani B. Characteristically, he sent a note to the Observatory office and before long the answer came (I think from Mrs. Fleming) that the spectrum of this star was A. I knew enough about it, even in these paleozoic days, to realize at once that there was an extreme inconsistency between what we would then have called "possible" values of the surface brightness and density. I must have shown that I was not only puzzled but crestfallen, at this exception to what looked like a very pretty rule of stellar characteristics; but Pickering smiled upon me, and said: "It is just these exceptions that lead to an advance in our knowledge", and so the white dwarfs entered the realm of study!

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the single-degenerate scenario, the accretion rate onto the white dwarf needs to be within a narrow range dependent on its mass so that the hydrogen burning on the surface of the white dwarf is stable. If the accretion rate is too low, novae on the surface of the white dwarf will blow away accreted material. If it’s too high, the white dwarf will expand and the white dwarf and companion star will be in a common envelope. This stops the growth of the white dwarf thus preventing it from reaching the Chandrasekhar limit and exploding. For the single-degenerate model its companion is expected to survive, but there is no strong evidence of such a star near Type Ia supernovae sites. In the double-degenerate scenario, white dwarfs need to be in very close binaries, otherwise their inspiral time is longer than the

3555: 15812: 1730: 2493: 2615: 3512: 2892: 3058:, it is slowed down in the denser environment. This slowed orbital speed is compensated with a decrease of the orbital distance between the red dwarf and the core of the red giant. The red dwarf spirals inwards towards the core and might merge with the core. If this does not happen and instead the common envelope is ejected, then the binary ends up in a close orbit, consisting of a white dwarf and a red dwarf. This type of binary is called a post-common envelope binary. The evolution of the PCEB continues as the two dwarf stars orbit closer and closer due to 2758:-Gaia proper motion. For GD 140 it is suspected to be a planet several times more massive than Jupiter and for LAWD 37 it is suspected to be a planet less massive than Jupiter. Additionally, WD 0141-675 was suspected to have a super-Jupiter with an orbital period of 33.65 days based on Gaia astrometry. This is remarkable because WD 0141-675 is polluted with metals and metal polluted white dwarfs have long be suspected to host giant planets that disturb the orbits of minor planets, causing the pollution. Both GD 140 and WD 0141 will be observed with 2585:, which is stronger for less massive white dwarfs. The Poynting–Robertson drag will also cause the dust to orbit closer and closer towards the white dwarf, until it will eventually sublimate and the disk will disappear. A debris disk will have a lifetime of around a few million years for white dwarfs hotter than 10,000 K. Colder white dwarfs can have disk-lifetimes of a few 10 million years, which is enough time to tidally disrupt a second rocky body and forming a second disk around a white dwarf, such as the two rings around 1941:

atmospheres. Those classified as DB, DC, DO, DZ, and cool DQ have helium-dominated atmospheres. Assuming that carbon and metals are not present, which spectral classification is seen depends on the effective temperature. Between approximately 100,000 K to 45,000 K, the spectrum will be classified DO, dominated by singly ionized helium. From 30,000 K to 12,000 K, the spectrum will be DB, showing neutral helium lines, and below about 12,000 K, the spectrum will be featureless and classified DC.

2501: 1963: 49: 1429: 2041: gauss (0.2 T to 100 kT). The large number of presently known magnetic white dwarfs is due to the fact that most white dwarfs are identified by low-resolution spectroscopy, which is able to reveal the presence of a magnetic field of 1 megagauss or more. Thus the basic identification process also sometimes results in discovery of magnetic fields. It has been estimated that at least 10% of white dwarfs have fields in excess of 1 million gauss (100 T). 15884: 15774: 14247: 13745: 437: 2416: 13735: 15848: 1910:, Jesse L. Greenstein and their coauthors in 1983 and has been subsequently revised several times. It classifies a spectrum by a symbol which consists of an initial D, a letter describing the primary feature of the spectrum followed by an optional sequence of letters describing secondary features of the spectrum (as shown in the adjacent table), and a temperature index number, computed by dividing 50,400 K by the 715:. If the star's distance is known, its absolute luminosity can also be estimated. From the absolute luminosity and distance, the star's surface area and its radius can be calculated. Reasoning of this sort led to the realization, puzzling to astronomers at the time, that due to their relatively high temperature and relatively low absolute luminosity, Sirius B and 40 Eridani B must be very dense. When 1520:. As a result, the interior of the white dwarf maintains an almost uniform temperature as it cools down, starting at approximately 10 K shortly after the formation of the white dwarf and reaching less than 10 K for the coolest known white dwarfs. An outer shell of non-degenerate matter sits on top of the degenerate core. The outermost layers, which have temperatures below 10 K, radiate roughly as a 1652: 15872: 14257: 15824: 2626: 1573: 15860: 1085:

created by the process of accretion onto white dwarfs. The significance of this finding is that there could be two types of supernovae, which could mean that the Chandrasekhar limit might not always apply in determining when a white dwarf goes supernova, given that two colliding white dwarfs could have a range of masses. This in turn would confuse efforts to use exploding white dwarfs as

15836: 15785: 661:; this is comparable to the Earth's radius of approximately 0.9% solar radius. A white dwarf, then, packs mass comparable to the Sun's into a volume that is typically a million times smaller than the Sun's; the average density of matter in a white dwarf must therefore be, very roughly, 1,000,000 times greater than the average density of the Sun, or approximately 10 2297:. Near the end of the period in which it undergoes fusion reactions, such a star will have a carbon–oxygen core which does not undergo fusion reactions, surrounded by an inner helium-burning shell and an outer hydrogen-burning shell. On the Hertzsprung–Russell diagram, it will be found on the asymptotic giant branch. It will then expel most of its outer material, creating a 2376:, that involve helium accretion by a white dwarf, have been proposed to be a channel for transformation of this type of stellar remnant. In this scenario, the carbon detonation produced in a Type Ia supernova is too weak to destroy the white dwarf, expelling just a small part of its mass as ejecta, but produces an asymmetric explosion that kicks the star, often known as a 1721:), often referred to as extremely low-mass white dwarfs (ELM WDs), are formed in binary systems. As a result of their hydrogen-rich envelopes, residual hydrogen burning via the CNO cycle may keep these white dwarfs hot on a long timescale. In addition, they remain in a bloated proto-white dwarf stage for up to 2 Gyr before they reach the cooling track. 2403: 3526: 1971:

accreted rocky planetesimals. The bulk composition of the accreted object can be measured from the strengths of the metal lines. For example, a 2015 study of the white dwarf Ton 345 concluded that its metal abundances were consistent with those of a differentiated, rocky planet whose mantle had been eroded by the host star's wind during its

1516:, because any absorption of a photon requires that an electron must transition to a higher empty state, which may not be possible as the energy of the photon may not be a match for the possible quantum states available to that electron, hence radiative heat transfer within a white dwarf is low; it does, however, have a high 2629: 2628: 2633: 2632: 2627: 1464:– at which the white dwarf can no longer be supported by electron degeneracy pressure. The graph on the right shows the result of such a computation. It shows how radius varies with mass for non-relativistic (blue curve) and relativistic (green curve) models of a white dwarf. Both models treat the white dwarf as a cold 423:. Despite these suspicions, the first non-classical white dwarf was not definitely identified until the 1930s. 18 white dwarfs had been discovered by 1939. Luyten and others continued to search for white dwarfs in the 1940s. By 1950, over a hundred were known, and by 1999, over 2,000 were known. Since then the 2634: 262:. Because the length of time it takes for a white dwarf to reach this state is calculated to be longer than the current age of the known universe (approximately 13.8 billion years), it is thought that no black dwarfs yet exist. The oldest known white dwarfs still radiate at temperatures of a few thousand 1644:(CIA) of hydrogen molecules colliding with helium atoms. This affects the optical red and infrared brightness of white dwarfs with a hydrogen or mixed hydrogen-helium atmosphere. This makes old white dwarfs with this kind of atmosphere bluer than the main cooling sequence. Hence these white dwarfs are called 2703:

is the first white dwarf observed with a disintegrating minor planet which transits the star. The disintegration of the planetesimal generates a debris cloud which passes in front of the star every 4.5 hours, causing a 5-minute-long fade in the star's optical brightness. The depth of the transit

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If a star is massive enough, its core will eventually become sufficiently hot to fuse carbon to neon, and then to fuse neon to iron. Such a star will not become a white dwarf, because the mass of its central, non-fusing core, initially supported by electron degeneracy pressure, will eventually exceed

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Most observed white dwarfs have relatively high surface temperatures, between 8,000 K and 40,000 K. A white dwarf, though, spends more of its lifetime at cooler temperatures than at hotter temperatures, so we should expect that there are more cool white dwarfs than hot white dwarfs. Once we

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We learn about the stars by receiving and interpreting the messages which their light brings to us. The message of the companion of Sirius when it was decoded ran: "I am composed of material 3,000 times denser than anything you have ever come across; a ton of my material would be a little nugget

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as double stars, the change of their motions would not surprise us; we should acknowledge them as necessary, and have only to investigate their amount by observation. But light is no real property of mass. The existence of numberless visible stars can prove nothing against the existence of numberless

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Observations have failed to note signs of accretion leading up to Type Ia supernovae, and this is now thought to be because the star is first loaded up to above the Chandrasekhar limit while also being spun up to a very high rate by the same process. Once the accretion stops, the star gradually

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White dwarfs whose primary spectral classification is DA have hydrogen-dominated atmospheres. They make up the majority, approximately 80%, of all observed white dwarfs. The next class in number is of DBs, approximately 16%. The hot, above 15,000 K, DQ class (roughly 0.1%) have carbon-dominated

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is thought to be the more likely scenario. Predicted rates of white dwarf-white dwarf mergers are comparable to the rate of Type Ia supernovae and would explain the lack of hydrogen in the spectra of Type Ia supernovae. However, the main mechanism for Type Ia supernovae remains an open question. In

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supports a white dwarf against gravitational collapse. The pressure depends only on density and not on temperature. Degenerate matter is relatively compressible; this means that the density of a high-mass white dwarf is much greater than that of a low-mass white dwarf and that the radius of a white

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dwarfs older than ~1 billion years or >7000 K with dusty infrared excess were not detected until the discovery of LSPM J0207+3331 in 2018, which has a cooling age of ~3 billion years. The white dwarf shows two dusty components that are being explained with two rings with different temperatures.

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that hotter, more luminous white dwarfs are easier to observe, we do find that decreasing the temperature range examined results in finding more white dwarfs. This trend stops when we reach extremely cool white dwarfs; few white dwarfs are observed with surface temperatures below 4,000 K, and

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atmosphere. After initially taking approximately 1.5 billion years to cool to a surface temperature of 7,140 K, cooling approximately 500 more kelvins to 6,590 K takes around 0.3 billion years, but the next two steps of around 500 kelvins (to 6,030 K and 5,550 K)

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together with the equation of state can then be solved to find the structure of the white dwarf at equilibrium. In the non-relativistic case, we will still find that the radius is inversely proportional to the cube root of the mass. Relativistic corrections will alter the result so that the radius

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of the white dwarf. The mechanism behind the pollution of white dwarfs in binaries was also explored as these systems are more likely to lack a major planet, but this idea cannot explain the presence of dust around single white dwarfs. While old white dwarfs show evidence of dust accretion, white

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suggest the presence of a dust cloud, which may be caused by cometary collisions. It is possible that infalling material from this may cause X-ray emission from the central star. Similarly, observations made in 2004 indicated the presence of a dust cloud around the young (estimated to have formed

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is released which provides a source of thermal energy that delays its cooling. Another possible mechanism that was suggested to explain the seeming delay in the cooling of some types of white dwarves is a solid–liquid distillation process: the crystals formed in the core are buoyant and float up,

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produced by those galaxies are 30 to 50 times less than what is expected to be produced by type Ia supernovas of that galaxy as matter accretes on the white dwarf from its encircling companion. It has been concluded that no more than 5 percent of the supernovae in such galaxies could be

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that existed in its progenitor star phase. A surface magnetic field of c. 100 gauss (0.01 T) in the progenitor star would thus become a surface magnetic field of c. 100·100 = 1 million gauss (100 T) once the star's radius had shrunk by a factor of 100. The first magnetic

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New research indicates that many white dwarfs – at least in certain types of galaxies – may not approach that limit by way of accretion. It has been postulated that at least some of the white dwarfs that become supernovae attain the necessary mass by colliding with one another. It may be that in

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surrounding the white dwarf, there are two ways a planet could end in a close orbit around stars of this kind: by surviving being engulfed by the star during its red giant phase, and then spiralling inward, or inward migration after the white dwarf has formed. The former case is implausible for

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I was visiting my friend and generous benefactor, Prof. Edward C. Pickering. With characteristic kindness, he had volunteered to have the spectra observed for all the stars – including comparison stars – which had been observed in the observations for stellar parallax which Hinks and I made at

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as the mass approaches the Chandrasekhar limit. Because the white dwarf is supported against gravity by quantum degeneracy pressure instead of by thermal pressure, adding heat to the star's interior increases its temperature but not its pressure, so the white dwarf does not expand and cool in

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Around 25–33% of white dwarfs have metal lines in their spectra, which is notable because any heavy elements in a white dwarf should sink into the star's interior in just a small fraction of the star's lifetime. The prevailing explanation for metal-rich white dwarfs is that they have recently

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matter from a companion star or other source, its radiation comes from its stored heat, which is not replenished. White dwarfs have an extremely small surface area to radiate this heat from, so they cool gradually, remaining hot for a long time. As a white dwarf cools, its surface temperature

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if it is able to take material from its companion fast enough to sustain fusion on its surface. On the other hand, phenomena in binary systems such as tidal interaction and star–disc interaction, moderated by magnetic fields or not, act on the rotation of accreting white dwarfs. In fact, the

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The visible radiation emitted by white dwarfs varies over a wide color range, from the whitish-blue color of an O, B or A-type main sequence star to the yellow-orange of a late K or early M-type star. White dwarf effective surface temperatures extend from over 150,000 K to barely under

1794:), and it is also hot: a white dwarf with surface temperature between 8,000 K and 16,000 K will have a core temperature between approximately 5,000,000 K and 20,000,000 K. The white dwarf is kept from cooling very quickly only by its outer layers' opacity to radiation. 11438:

Wang, Ting-Gui; Jiang, Ning; Ge, Jian; Cutri, Roc M.; Jiang, Peng; Sheng, Zhengfeng; Zhou, Hongyan; Bauer, James; Mainzer, Amy; Wright, Edward L. (9 October 2019). "An On-going Mid-infrared Outburst in the White Dwarf 0145+234: Catching in Action of Tidal Disruption of an Exoasteroid?".

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is thought to cause this purity by gravitationally separating the atmosphere so that heavy elements are below and the lighter above. This atmosphere, the only part of the white dwarf visible to us, is thought to be the top of an envelope which is a residue of the star's envelope in the

2635: 2463:; in these cases, the lifetime is estimated to be no more than 10 years. If protons do decay, the mass of a white dwarf will decrease very slowly with time as its nuclei decay, until it loses enough mass to become a nondegenerate lump of matter, and finally disappears completely. 2180:; in 1965 and 1966, and was observed to vary with a period of approximately 12.5 minutes. The reason for this period being longer than predicted is that the variability of HL Tau 76, like that of the other pulsating variable white dwarfs known, arises from non-radial 952:

The existence of a limiting mass that no white dwarf can exceed without collapsing to a neutron star is another consequence of being supported by electron degeneracy pressure. Such limiting masses were calculated for cases of an idealized, constant density star in 1929 by

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During validation of epoch astrometry for Gaia DR4, an error was discovered, that had already had an impact on the Gaia DR3 non-single star results. We can conclude that the solutions for WD 0141-675 are false-positives as far as Gaia non-single star processing is

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Rotating white dwarfs and the estimates of their diameter in terms of the angular velocity of rotation has been treated in the rigorous mathematical literature. The fine structure of the free boundary of white dwarfs has also been analysed mathematically rigorously.

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A less common observable evidence is infrared excess due to a flat and optically thick debris disk, which is found in around 1–4% of white dwarfs. The first white dwarf with infrared excess was discovered by Zuckerman and Becklin in 1987 in the near-infrared around

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low-mass bodies, as they are unlikely to survive being absorbed by their stars. In the latter case, the planets would have to expel so much orbital energy as heat, through tidal interactions with the white dwarf, that they would likely end as uninhabitable embers.

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between the ionic species in the plasma mixture can release a similar or even greater amount of energy. This energy release was first confirmed in 2019 after the identification of a pile up in the cooling sequence of more than 15,000 white dwarfs observed with the

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The least common observable evidence of planetary systems are detected major or minor planets. Only a handful of giant planets and a handful of minor planets are known around white dwarfs. It is a growing list with discoveries of around 6 exoplanets expected with

2257:, it will never become hot enough to ignite and fuse helium in its core. It is thought that, over a lifespan that considerably exceeds the age of the universe (c. 13.8 billion years), such a star will eventually burn all its hydrogen, for a while becoming a 258:, will lessen and redden with time. Over a very long time, a white dwarf will cool and its material will begin to crystallize, starting with the core. The star's low temperature means it will no longer emit significant heat or light, and it will become a cold 2576:

and later confirmed as a debris disk. White dwarfs hotter than 27,000 K sublimate all the dust formed by tidally disrupting a rocky body, preventing the formation of a debris disk. In colder white dwarfs, a rocky body might be tidally disrupted near the

3009:. It is also likely that instead of a Type Ia supernova, the merger of two white dwarfs will lead to core-collapse. As a white dwarf accretes material quickly, the core can ignite off-center which leads to gravitational instabilities which could create a 2404: 2405: 2265:

nuclei. Due to the very long time this process takes, it is not thought to be the origin of the observed helium white dwarfs. Rather, they are thought to be the product of mass loss in binary systems or mass loss due to a large planetary companion.

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Mullally, Susan Elizabeth; Mullally, Fergal; Albert, Loic; Barclay, Thomas; Debes, John Henry; Kilic, Mukremin; Kuchner, Marc Jason; Quintana, Elisa V.; Reach, William (2021). "A Search for the Giant Planets that Drive White Dwarf Accretion".

3117:(or giant) and a white dwarf. The binary Sirius AB is probably the most famous example. White dwarfs can also exist as binaries or multiple star systems that only consist of white dwarfs. An example of a resolved triple white dwarf system is 2523:

absorption lines. 27–50% of white dwarfs show a spectrum polluted with metals, but these heavy elements settle out in the atmosphere of white dwarfs colder than 20,000 K. The most widely accepted hypothesis is that this pollution comes from

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Vanderburg, Andrew; Johnson, John Asher; Rappaport, Saul; Bieryla, Allyson; Irwin, Jonathan; Lewis, John Arban; Kipping, David; Brown, Warren R.; Dufour, Patrick (22 October 2015). "A disintegrating minor planet transiting a white dwarf".

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Eisenstein, Daniel J.; Liebert, James; Harris, Hugh C.; Kleinman, S. J.; Nitta, Atsuko; Silvestri, Nicole; et al. (2006). "A catalog of spectroscopically confirmed white dwarfs from the Sloan Digital Sky Survey, data release 4".

2911:(securely known) fastest-spinning white dwarfs are members of binary systems (the fastest one being the white dwarf in CTCV J2056-3014). A close binary system of two white dwarfs can lose angular momentum and radiate energy in the form of 1452:

which describes the relationship between density and pressure in the white dwarf material. If the density and pressure are both set equal to functions of the radius from the center of the star, the system of equations consisting of the

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Although thin, these outer layers determine the thermal evolution of the white dwarf. The degenerate electrons in the bulk of a white dwarf conduct heat well. Most of a white dwarf's mass is therefore at almost the same temperature

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decreases, the radiation which it emits reddens, and its luminosity decreases. Since the white dwarf has no energy sink other than radiation, it follows that its cooling slows with time. The rate of cooling has been estimated for a

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Mullally, Susan E.; Debes, John; Cracraft, Misty; Mullally, Fergal; Poulsen, Sabrina; Albert, Loic; Thibault, Katherine; Reach, William T.; Hermes, J. J.; Barclay, Thomas; Kilic, Mukremin; Quintana, Elisa V. (24 January 2024).

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Gates, Evalyn; Gyuk, Geza; Harris, Hugh C.; Subbarao, Mark; Anderson, Scott; Kleinman, S. J.; Liebert, James; Brewington, Howard; et al. (2004). "Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey".

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Kanaan, A.; Nitta, A.; Winget, D. E.; Kepler, S. O.; Montgomery, M. H.; Metcalfe, T. S.; et al. (2005). "Whole Earth Telescope observations of BPM 37093: A seismological test of crystallization theory in white dwarfs".

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Cheng, Sihao; Schlaufman, Kevin C.; Caiazzo, Ilaria (1 August 2024). "A Candidate Giant Planet Companion to the Massive, Young White Dwarf GALEX J071816.4+373139 Informs the Occurrence of Giant Planets Orbiting B Stars".

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Jordan, George C. IV.; Perets, Hagai B.; Fisher, Robert T.; van Rossum, Daniel R. (2012). "Failed-detonation Supernovae: Subluminous Low-velocity Ia Supernovae and their Kicked Remnant White Dwarfs with Iron-rich Cores".

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Compression of a white dwarf will increase the number of electrons in a given volume. Applying the Pauli exclusion principle, this will increase the kinetic energy of the electrons, thereby increasing the pressure. This

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Gaia Collaboration; Arenou, F.; Babusiaux, C.; Barstow, M. A.; Faigler, S.; Jorissen, A.; Kervella, P.; Mazeh, T.; Mowlavi, N.; Panuzzo, P.; Sahlmann, J.; Shahaf, S.; Sozzetti, A.; Bauchet, N.; Damerdji, Y. (2023).

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systems can accrete material from a companion star, increasing both their mass and their density. As their mass approaches the Chandrasekhar limit, this could theoretically lead to either the explosive ignition of

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The white dwarf companion of Sirius, Sirius B, was next to be discovered. During the nineteenth century, positional measurements of some stars became precise enough to measure small changes in their location.

2784:(LAWD 83). If confirmed they would be the first directly imaged planets that likely formed from circumstellar disk material, representing a new population of directly imaged giant planets that are more similar to 1229: 1015:. (Near the beginning of the 20th century, there was reason to believe that stars were composed chiefly of heavy elements, so, in his 1931 paper, Chandrasekhar set the average molecular weight per electron, 692:

system, as is the case for Sirius B or 40 Eridani B, it is possible to estimate its mass from observations of the binary orbit. This was done for Sirius B by 1910, yielding a mass estimate of

2630: 2222:. These variables all exhibit small (1–30%) variations in light output, arising from a superposition of vibrational modes with periods of hundreds to thousands of seconds. Observation of these variations gives 920:, also introduced in 1926 to determine the statistical distribution of particles which satisfy the Pauli exclusion principle. At zero temperature, therefore, electrons can not all occupy the lowest-energy, or 3081:. These surface explosions can be repeated as long as the white dwarf's core remains intact. This weaker kind of repetitive cataclysmic phenomenon is called a (classical) nova. Astronomers have also observed 3076:

Before accretion of material pushes a white dwarf close to the Chandrasekhar limit, accreted hydrogen-rich material on the surface may ignite in a less destructive type of thermonuclear explosion powered by

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Blinnikov, S. I.; Röpke, F. K.; Sorokina, E. I.; Gieseler, M.; Reinecke, M.; Travaglio, C.; Hillebrandt, W.; Stritzinger, M. (2006). "Theoretical light curves for deflagration models of type Ia supernova".

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Lawrence, G. M.; Ostriker, J. P.; Hesser, J. E. (1967). "Ultrashort-Period Stellar Oscillations. I. Results from White Dwarfs, Old Novae, Central Stars of Planetary Nebulae, 3c 273, and Scorpius XR-1".

2005:, was never generally accepted, and by the 1950s even Blackett felt it had been refuted. In the 1960s, it was proposed that white dwarfs might have magnetic fields due to conservation of total surface 1622:, has a surface temperature of approximately 3,050 K. The reason for this is that the Universe's age is finite; there has not been enough time for white dwarfs to cool below this temperature. The 239:— beyond which it cannot be supported by electron degeneracy pressure. A carbon–oxygen white dwarf that approaches this mass limit, typically by mass transfer from a companion star, may explode as a 3062:

and by releasing gravitational waves. The binary might evolve at some point into a cataclysmic variable, and therefore post-common envelope binaries are sometimes called pre-cataclysmic variables.

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from their host planet could cause white dwarf pollution with dust. Either the liberation could cause asteroids to be scattered towards the white dwarf or the exomoon could be scattered into the

2245:. The composition of the white dwarf produced will depend on the initial mass of the star. Current galactic models suggest the Milky Way galaxy currently contains about ten billion white dwarfs. 254:

A white dwarf is very hot when it forms, but because it has no source of energy, it will gradually cool as it radiates its energy away. This means that its radiation, which initially has a high

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Su, K. Y. L.; Chu, Y.-H.; Rieke, G. H.; Huggins, P. J.; Gruendl, R.; Napiwotzki, R.; Rauch, T.; Latter, W. B.; Volk, K. (2007). "A Debris Disk around the Central Star of the Helix Nebula?".

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Spergel, D.N.; Bean, R.; Doré, O.; Nolta, M.R.; Bennett, C.L.; Dunkley, J.; et al. (2007). "Wilkinson Microwave Anisotropy Probe (WMAP) three year results: Implications for cosmology".

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of hypothetical Earth-like planets that could have migrated inward or formed there. As a white dwarf has a size similar to that of a planet, these kinds of transits would produce strong

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flame consumes much of the white dwarf in a few seconds, causing a Type Ia supernova explosion that obliterates the star. In another possible mechanism for Type Ia supernovae, the

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per cubic centimetre. A typical white dwarf has a density of between 10 and 10 g/cm. White dwarfs are composed of one of the densest forms of matter known, surpassed only by other

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Kepler, S.O.; Pelisoli, I.; Jordan, S.; Kleinman, S.J.; Koester, D.; Kuelebi, B.; Pecanha, V.; Castanhiera, B.G.; Nitta, A.; Costa, J.E.S.; Winget, D.E.; Kanaan, A.; Fraga, L. (2013).

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González Hernández, J.I.; Ruiz-Lapuente, P.; Tabernero, H. M.; Montes, D.; Canal, R.; Méndez, J.; Bedin, L. R. (2012). "No surviving evolved companions of the progenitor of SN 1006".

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exhibit abundances of neon, magnesium, and other intermediate-mass elements which appear to be only explicable by the accretion of material onto an oxygen–neon–magnesium white dwarf.

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limited by normal matter. Eddington wondered what would happen when this plasma cooled and the energy to keep the atoms ionized was no longer sufficient. This paradox was resolved by

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The material in a white dwarf no longer undergoes fusion reactions, so the star has no source of energy. As a result, it cannot support itself by the heat generated by fusion against

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Di Stefano, R.; Nelson, L. A.; Lee, W.; Wood, T. H.; Rappaport, S. (1997). "Luminous Supersoft X-ray Sources as Type Ia Progenitors". In P. Ruiz-Lapuente; R. Canal; J. Isern (eds.).

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Casewell, S. L.; Debes, J.; Dupuy, T. J.; Dufour, P.; Bonsor, A.; Rebassa-Mansergas, A.; Murillo-Ojeda, R.; French, J. R.; Xu, Siyi (许偲艺); Martin, E.; Manjavacas, E. (8 April 2024).

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Althaus, L. G.; García-Berro, E.; Isern, J.; Córsico, A. H.; Miller Bertolami, M. M. (January 2012). "New phase diagrams for dense carbon-oxygen mixtures and white dwarf evolution".

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lines in its spectrum and an effective temperature of 15,000 K could be given the classification of DB3, or, if warranted by the precision of the temperature measurement, DB3.5.

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These computations all assume that the white dwarf is non-rotating. If the white dwarf is rotating, the equation of hydrostatic equilibrium must be modified to take into account the

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passing close to the white dwarf. Some estimations based on the metal content of the atmospheres of the white dwarfs consider that at least 15% of them may be orbited by planets or

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Elms, Abbigail K.; Tremblay, Pier-Emmanuel; Gänsicke, Boris T.; Koester, Detlev; Hollands, Mark A.; Gentile Fusillo, Nicola Pietro; Cunningham, Tim; Apps, Kevin (1 December 2022).

111:. There are currently thought to be eight white dwarfs among the hundred star systems nearest the Sun. The unusual faintness of white dwarfs was first recognized in 1910. The name 3093:

collapses onto the star, rather than through a release of energy due to fusion. In general, binary systems with a white dwarf accreting matter from a stellar companion are called

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in cycle 2 with the aim to detect infrared excess caused by the planets. However, the planet candidate at WD 0141-675 was found to be a false positive caused by a software error.

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Sion, Edward M.; Holberg, J.B.; Oswalt, Terry D.; McCook, George P.; Wasatonic, Richard (2009). "The White Dwarfs Within 20 Parsecs of the Sun: Kinematics and Statistics".

7427:

Blouin, Simon; Daligault, Jérôme; Saumon, Didier; Bédard, Antoine; Brassard, Pierre (August 2020). "Toward precision cosmochronology: A new C/O phase diagram for white dwarfs".

12930:

Post-common-envelope binaries from SDSS – I. 101 white dwarf main-sequence binaries with multiple Sloan Digital Sky Survey spectroscopy: Post-common-envelope binaries from SDSS

6679:

Gates, E.; Gyuk, G.; Harris, H. C.; Subbarao, M.; Anderson, S.; Kleinman, S. J.; et al. (2004). "Discovery of New Ultracool White Dwarfs in the Sloan Digital Sky Survey".

8581:

Buckley, D.A.H.; Meintjes, P.J.; Potter, S.B.; Marsh, T.R.; Gänsicke, B.T. (23 January 2017). "Polarimetric evidence of a white dwarf pulsar in the binary system AR Scorpii".

7036:

Metcalfe, T. S.; Montgomery, M. H.; Kanaan, A. (20 April 2004). "Testing White Dwarf Crystallization Theory with Asteroseismology of the Massive Pulsating DA Star BPM 37093".

10414:

Reach, William T.; Kuchner, Marc J.; Von Hippel, Ted; Burrows, Adam; Mullally, Fergal; Kilic, Mukremin; Winget, D. E. (2005). "The Dust Cloud around the White Dwarf G29-38".

2516:

is inherited from its progenitor star and may interact with the white dwarf in various ways. There are several indications that a white dwarf has a remnant planetary system.

2406: 1100:, a graph of stellar luminosity versus color or temperature. They should not be confused with low-luminosity objects at the low-mass end of the main sequence, such as the 11304: 2487: 2419:

Internal structures of white dwarfs. To the left is a newly formed white dwarf, in the center is a cooling and crystallizing white dwarf, and the right is a black dwarf.

12434: 8475:

Landstreet, J.D.; Bagnulo, S.; Valyavin, G.G.; Fossati, L.; Jordan, S.; Monin, D.; Wade, G.A. (2012). "On the incidence of weak magnetic fields in DA white dwarfs".

4108: 2815: 2643: 2214:

stars, with atmospheres dominated by helium, carbon, and oxygen. GW Vir stars are not, strictly speaking, white dwarfs, but are stars which are in a position on the

1274: 961:. This value was corrected by considering hydrostatic equilibrium for the density profile, and the presently known value of the limit was first published in 1931 by 2435:

escape into intergalactic space. White dwarfs should generally survive galactic dispersion, although an occasional collision between white dwarfs may produce a new

10846:

Debes, John H.; Walsh, Kevin J.; Stark, Christopher (24 February 2012). "The Link Between Planetary Systems, Dusty White Dwarfs, and Metal-Polluted White Dwarfs".

2301:, until only the carbon–oxygen core is left. This process is responsible for the carbon–oxygen white dwarfs which form the vast majority of observed white dwarfs. 2870:. Newer research casts some doubts on this idea, given that the close orbits of those hypothetical planets around their parent stars would subject them to strong 14156: 13720: 4554: 4511: 4421: 4375: 4329: 4202: 3785: 3635: 2715:

by the strong ultraviolet radiation of the hot white dwarf. Part of the evaporated material is being accreted in a gaseous disk around the white dwarf. The weak

2687:. Other suggested ideas of how white dwarfs are polluted with dust involve the scattering of asteroids by planets or via planet-planet scattering. Liberation of 1645: 7481: 3511: 3901:

Liebert, James; Bergeron, P.; Eisenstein, D.; Harris, H. C.; Kleinman, S. J.; Nitta, A.; Krzesinski, J. (2004). "A helium white dwarf of extremely low mass".

1995:

in 1947 as a consequence of a physical law he had proposed which stated that an uncharged, rotating body should generate a magnetic field proportional to its

11413: 1697:

had crystallized. Other work gives a crystallized mass fraction of between 32% and 82%. As a white dwarf core undergoes crystallization into a solid phase,

991:

is the average molecular weight per electron of the star. As the carbon-12 and oxygen-16 which predominantly compose a carbon–oxygen white dwarf both have

732:

that you could put in a matchbox." What reply can one make to such a message? The reply which most of us made in 1914 was — "Shut up. Don't talk nonsense."

12641: 1496:

in 1947, there is no limit to the mass for which it is possible for a model white dwarf to be in static equilibrium. Not all of these model stars will be

1334: 9420: 1546:

that of the Sun's. Hot white dwarfs, with surface temperatures in excess of 30,000 K, have been observed to be sources of soft (i.e., lower-energy)

9393: 3105:, both of which feature highly magnetic white dwarfs. Both fusion- and accretion-powered cataclysmic variables have been observed to be X-ray sources. 2679:, that would have survived the red giant phase of their star but losing their outer layers and, given those planetary remnants would likely be made of 4855: 4251: 3682: 2777: 1640:. No black dwarfs are thought to exist yet. At very low temperatures (<4000 K) white dwarfs with hydrogen in their atmosphere will be affected by 3133:

and brown dwarfs that orbit them, the white dwarfs are faint. This allows astronomers to study these brown dwarfs or exoplanets in more detail. The

3046:

A post-common envelope binary (PCEB) is a binary consisting of a white dwarf and a closely tidally-locked red dwarf (in other cases this might be a

11242:

Becklin, E. E.; Zuckerman, B.; Farihi, J. (10 February 2008). "Spitzer IRAC Observations of White Dwarfs. I. Warm Dust at Metal-Rich Degenerates".

10209:

Klein, Beth L.; Doyle, Alexandra E.; Zuckerman, B.; Dufour, P.; Blouin, Simon; Melis, Carl; Weinberger, Alycia J.; Young, Edward D. (1 June 2021).

2781: 719:

estimated the density of a number of visual binary stars in 1916, he found that 40 Eridani B had a density of over 25,000 times the

215:) white dwarf may form. Stars of very low mass will be unable to fuse helium; hence, a helium white dwarf may form by mass loss in binary systems. 2353:. Although a few white dwarfs have been identified which may be of this type, most evidence for the existence of such comes from the novae called 13710: 8657: 3623: 3118: 1524:. A white dwarf remains visible for a long time, as its tenuous outer atmosphere slowly radiates the thermal content of the degenerate interior. 10467:

Steckloff, Jordan K.; Debes, John; Steele, Amy; Johnson, Brandon; Adams, Elisabeth R.; Jacobson, Seth A.; Springmann, Alessondra (1 June 2021).

3840: 12696:

Giammichele, N.; Bergeron, P.; Dufour, P. (April 2012). "Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs".

9322: 3028:

of 1572 was also a type Ia supernova, and its remnant has been detected. A close candidate to being a survivor of a type Ia supernova is

2964:, a carbon–oxygen white dwarf accretes mass and compresses its core by pulling mass from a companion non-degenerate star. It is believed that 5834: 9859: 9285:

Nelemans, G.; Tauris, T. M. (1998). "Formation of undermassive single white dwarfs and the influence of planets on late stellar evolution".

5280: 1693:

yielded a potential test of the crystallization theory, and in 2004, observations were made that suggested approximately 90% of the mass of

1648:. White dwarfs with hydrogen-poor atmospheres, such as WD J2147–4035, are less affected by CIA and therefore have a yellow to orange color. 5476: 1138: 9209:

Sarna, M. J.; Ergma, E.; Gerškevitš, J. (2001). "Helium core white dwarf evolution – including white dwarf companions to neutron stars".

3963: 2466:

A white dwarf can also be cannibalized or evaporated by a companion star, causing the white dwarf to lose so much mass that it becomes a

2423:

A white dwarf is stable once formed and will continue to cool almost indefinitely, eventually to become a black dwarf. Assuming that the

12674: 5677: 4961: 8832:

Nagel, T.; Werner, K. (2004). "Detection of non-radial g-mode pulsations in the newly discovered PG 1159 star HE 1429-1209".

4910:

Shipman, H.L. (1979). "Masses and radii of white-dwarf stars. III – Results for 110 hydrogen-rich and 28 helium-rich stars".

1776:

of the star's total mass, which, if the atmosphere is hydrogen-dominated, is overlain by a hydrogen-rich layer with mass approximately

5977: 1630:

found in this way is 8 billion years. A white dwarf will eventually, in many trillions of years, cool and become a non-radiating

1580:

B (center), its A-class companion IK Pegasi A (left) and the Sun (right). This white dwarf has a surface temperature of 35,500 K.

1488:. For a uniformly rotating white dwarf, the limiting mass increases only slightly. If the star is allowed to rotate nonuniformly, and 13224: 8275:

Ginzburg, V. L.; Zheleznyakov, V. V.; Zaitsev, V. V. (1969). "Coherent mechanisms of radio emission and magnetic models of pulsars".

1641: 9501:"Evolution of 8–10 solar mass stars toward electron capture supernovae. I – Formation of electron-degenerate O + NE + MG cores" 2902:

If a white dwarf is in a binary star system and is accreting matter from its companion, a variety of phenomena may occur, including

60:. Sirius B, which is a white dwarf, can be seen as a faint point of light to the lower left of the much brighter Sirius A. 13996: 11640: 9540:

Werner, K.; Rauch, T.; Barstow, M. A.; Kruk, J. W. (2004). "Chandra and FUSE spectroscopy of the hot bare stellar core H?1504+65".

9230: 7090: 2747: 2455:

between 10 and 10 years. If these theories are not valid, the proton might still decay by complicated nuclear reactions or through

7563:

Istrate, A. G.; Tauris, T. M.; Langer, N.; Antoniadis, J. (2014). "The timescale of low-mass proto-helium white dwarf evolution".

6181:

Saumon, Didier; Blouin, Simon; Tremblay, Pier-Emmanuel (November 2022). "Current challenges in the physics of white dwarf stars".

5023:

Liebert, James; Young, P. A.; Arnett, D.; Holberg, J. B.; Williams, K. A. (2005). "The age and progenitor mass of Sirius B".

2349:, provided that its core does not collapse, and provided that fusion does not proceed so violently as to blow apart the star in a 1906:

in 1941, and various classification schemes have been proposed and used since then. The system currently in use was introduced by

12513:

Krause, Oliver; et al. (2008). "Tycho Brahe's 1572 supernova as a standard type Ia as revealed by its light-echo spectrum".

7870:

Kepler, S. O.; Kleinman, S. J.; Nitta, A.; Koester, D.; Castanheira, B. G.; Giovannini, O.; Costa, A. F. M.; Althaus, L. (2007).

3590: 1120: 12125: 12098: 11401:

Gänsicke, Boris T.; Schreiber, Matthias R.; Toloza, Odette; Gentile Fusillo, Nicola P.; Koester, Detlev; Manser, Christopher J.

10078:

Debes, John H.; Thévenot, Melina; Kuchner, Marc J.; Burgasser, Adam J.; Schneider, Adam C.; Meisner, Aaron M.; Gagné, Jonathan;

3967: 3085:, which have smaller, more frequent luminosity peaks than the classical novae. These are thought to be caused by the release of 13781: 9183: 6794:

Winget, D. E.; Hansen, C. J.; Liebert, James; Van Horn, H. M.; Fontaine, G.; Nather, R. E.; Kepler, S. O.; Lamb, D. Q. (1987).

3716: 2803:, which was discovered in 2009. This is seen as perhaps the first case of linking white dwarf pollution with the presence of a 2176:

with a period of around 10 seconds, but searches in the 1960s failed to observe this. The first variable white dwarf found was

363:(α Canis Minoris) were changing their positions periodically. In 1844 he predicted that both stars had unseen companions: 11312: 9929: 7990:

Xu, S.; Jura, M.; Koester, D.; Klein, B.; Zuckerman, B. (2013). "Discovery of Molecular Hydrogen in White Dwarf Atmospheres".

15657: 14220: 13420: 12866: 12018: 10669: 9899: 7739: 6858: 6537: 6351: 5737: 5451: 5323: 3756: 3525: 1677:– that is initially in a fluid state. It was theoretically predicted in the 1960s that at a late stage of cooling, it should 2394:

white dwarfs would be smaller than the carbon–oxygen kind of similar mass and would cool and crystallize faster than those.

1749:

dominated. The dominant element is usually at least 1,000 times more abundant than all other elements. As explained by

12438: 9805:

Seager, S.; Kuchner, M.; Hier-Majumder, C.; Militzer, B. (19 July 2007). "Mass-Radius Relationships for Solid Exoplanets".

5948: 2993:

in which carbon fusion is then ignited. In both cases, the white dwarfs are not expected to survive the Type Ia supernova.

10360:

Zuckerman, B.; Becklin, E. E. (1 November 1987). "Excess infrared radiation from a white dwarf—an orbiting brown dwarf?".

8679: 5914: 182:, it will leave behind a core, which is the remnant white dwarf. Usually, white dwarfs are composed of carbon and oxygen ( 12575: 9752:

Adams, Fred C.; Laughlin, Gregory (1997). "A dying universe: The long-term fate and evolution of astrophysical objects".

3712: 1448:

For a more accurate computation of the mass-radius relationship and limiting mass of a white dwarf, one must compute the

178:

K), an inert mass of carbon and oxygen will build up at its center. After such a star sheds its outer layers and forms a

8984:

Heger, A.; Fryer, C. L.; Woosley, S. E.; Langer, N.; Hartmann, D. H. (2003). "How Massive Single Stars End Their Life".

226:, causing it to be extremely dense. The physics of degeneracy yields a maximum mass for a non-rotating white dwarf, the 15632: 14951: 14230: 9951:

Koester, D.; Gänsicke, B. T.; Farihi, J. (1 June 2014). "The frequency of planetary debris around young white dwarfs".

7480:

Tremblay, P.-E.; Fontaine, G.; Fusillo, N. P. G.; Dunlap, B. H.; Gänsicke, B. T.; Hollands, M. H.; et al. (2019).

4993: 2766: 926:, state; some of them would have to occupy higher-energy states, forming a band of lowest-available energy states, the 9595:"On the interpretation and implications of nova abundances: An abundance of riches or an overabundance of enrichments" 7624: 12958: 4046:

Heger, A.; Fryer, C.L.; Woosley, S.E.; Langer, N.; Hartmann, D.H. (2003). "How massive single stars end their life".

3836: 2519:

The most common observable evidence of a remnant planetary system is pollution of the spectrum of a white dwarf with

2386:. The matter processed in the failed detonation is re-accreted by the white dwarf with the heaviest elements such as 2106: 786: 381: 17: 4957: 965:

in his paper "The Maximum Mass of Ideal White Dwarfs". For a non-rotating white dwarf, it is equal to approximately

8197:

Lovell, B. (1975). "Patrick Maynard Stuart Blackett, Baron Blackett, of Chelsea. 18 November 1897 – 13 July 1974".

7617:"First Giant Planet around White Dwarf Found – ESO observations indicate the Neptune-like exoplanet is evaporating" 6968:

Barrat, J. L.; Hansen, J. P.; Mochkovitch, R. (1988). "Crystallization of carbon-oxygen mixtures in white dwarfs".

15811: 11402: 5385:

Hoddeson, L. H.; Baym, G. (1980). "The Development of the Quantum Mechanical Electron Theory of Metals: 1900–28".

2675:, or at least their debris. Another suggested idea is that white dwarfs could be orbited by the stripped cores of 2492: 707:. Since hotter bodies radiate more energy than colder ones, a star's surface brightness can be estimated from its 15344: 14179: 13715: 13458: 11527:"Stellar and substellar companions from Gaia EDR3. Proper-motion anomaly and resolved common proper-motion pairs" 8528:

Liebert, James; Bergeron, P.; Holberg, J. B. (2003). "The True Incidence of Magnetism Among Field White Dwarfs".

2215: 2065: 1623: 1129:

The relationship between the mass and radius of low-mass white dwarfs can be estimated using the nonrelativistic

1097: 441: 411:, indicating that they could be suspected to be low-luminosity stars close to the Earth, and hence white dwarfs. 10644: 8087:

Wilson, D.J.; Gänsicke, B.T.; Koester, D.; Toloza, O.; Pala, A. F.; Breedt, E.; Parsons, S.G. (11 August 2015).

4849:; Kleinman, S.J.; Nitta, A.; Koester, D.; Castanheira, B.G.; Giovannini, O.; Costa, A.F.M.; Althaus, L. (2007). 174:. If a red giant has insufficient mass to generate the core temperatures required to fuse carbon (around 1 15637: 15274: 15258: 14293: 14260: 12645: 10567:

Sanderson, Hannah; Bonsor, Amy; Mustill, Alexander J (1 June 2022). "The galactic population of white dwarfs".

3086: 2833:, has a temperature of about 400 Kelvin (127 °C; 260 °F) and is unresolved. The white dwarf has a mass of 1.29 12928:

Rebassa-Mansergas, A.; Gänsicke, B. T.; Rodríguez-Gil, P.; Schreiber, M. R.; Koester, D. (28 November 2007). "

9424: 1626:

can therefore be used to find the time when stars started to form in a region; an estimate for the age of our

15684: 15551: 14205: 14184: 12989:— Discusses how to find mass-radius relations and mass limits for white dwarfs using simple energy arguments. 9397: 9093:

Brown, J. M.; Kilic, M.; Brown, W. R.; Kenyon, S. J. (2011). "The binary fraction of low-mass white dwarfs".

4171: 2878:. Another suggested constraint to this idea is the origin of those planets. Leaving aside formation from the 1745:

typically shows that their emitted light comes from an atmosphere which is observed to be either hydrogen or

2443:. The subsequent lifetime of white dwarfs is thought to be on the order of the hypothetical lifetime of the 1305:

for the kinetic energy, it is non-relativistic. When the electron velocity in a white dwarf is close to the

15667: 15618: 15593: 14886: 13617: 13489: 13305: 12937: 12929: 8716:"Mapping the Instability Domains of GW Vir Stars in the Effective Temperature–Surface Gravity Diagram" 5212:

Celotti, A.; Miller, J.C.; Sciama, D.W. (1999). "Astrophysical evidence for the existence of black holes".

3059: 2850:

It has been proposed that white dwarfs with surface temperatures of less than 10,000 K could harbor a

2258: 1729: 944: 223: 39: 13244:

Dufour, P.; Liebert, James; Fontaine, G.; Behara, N. (2007). "White dwarf stars with carbon atmospheres".

7929:

Dufour, P.; Liebert, James; Fontaine, G.; Behara, N. (2007). "White dwarf stars with carbon atmospheres".

6874:

Bergeron, P.; Kilic, Mukremin; Blouin, Simon; Bédard, A.; Leggett, S. K.; Brown, Warren R. (1 July 2022).

3867:

On possible oxygen / neon white dwarfs: H1504+65 and the white dwarf donors in ultracompact X-ray binaries

3674: 15608: 15588: 14174: 14017: 13682: 13677: 12580: 10084:"A 3 Gyr White Dwarf with Warm Dust Discovered via the Backyard Worlds: Planet 9 Citizen Science Project" 7840: 6239:

Sion, E. M.; Greenstein, J. L.; Landstreet, J. D.; Liebert, James; Shipman, H. L.; Wegner, G. A. (1983).

3041: 3024:

is thought to have been a type Ia supernova from a white dwarf, possibly the merger of two white dwarfs.

2989:, two carbon–oxygen white dwarfs in a binary system merge, creating an object with mass greater than the 2614: 2582: 1702:

thereby displacing heavier liquid downward, thus causing a net release of gravitational energy. Chemical

1637: 1477:, has been set equal to 2. Radius is measured in standard solar radii and mass in standard solar masses. 1124: 14971: 14125: 12377: 11997:. NATO Science Series C: Mathematical and physical sciences. Vol. 486. Springer. pp. 148–149. 15914: 15909: 15802: 15672: 15603: 15573: 13971: 13774: 12749:

Delfosse, Xavier; et al. (April 1999). "New neighbours. I. 13 new companions to nearby M dwarfs".

2759: 2598: 2076:, resulting in what has been initially described as "magnetized matter" in research published in 2012. 962: 917: 73: 12320: 11462:"Stellar and substellar companions of nearby stars from Gaia DR2. Binarity from proper motion anomaly" 8637: 6514:. The Hubble Deep Field: Proceedings of the Space Telescope Science Institute Symposium. p. 252. 2891: 2858:

that would last upwards of 3 billion years. This is so close that any habitable planets would be

2310:

the largest possible mass supportable by degeneracy pressure. At this point the core of the star will

15679: 15556: 15533: 15115: 14564: 14559: 14554: 14549: 14544: 14539: 14189: 13703: 13607: 13413: 12036:"CTCV J2056-3014: An X-Ray-faint Intermediate Polar Harboring an Extremely Fast-spinning White Dwarf" 11041:

Bonsor, Amy; Gänsicke, Boris T.; Veras, Dimitri; Villaver, Eva; Mustill, Alexander J. (21 May 2018).

8324: 8240:

Landstreet, John D. (1967). "Synchrotron radiation of neutrinos and its astrophysical significance".

5084: 5025: 4912: 4790: 3903: 3832: 3071: 2719:

as well as other lines in the spectrum of the white dwarf revealed the presence of the giant planet.

2528:

rocky bodies. The first observation of a metal-polluted white dwarf was by van Maanen in 1917 at the

1536:); this surface temperature range corresponds to a luminosity from over 100 times the Sun's to under 909: 662: 4788:

Kilic, M.; Allende Prieto, C.; Brown, Warren R.; Koester, D. (2007). "The lowest mass white dwarf".

2929:

The mass of an isolated, nonrotating white dwarf cannot exceed the Chandrasekhar limit of ~1.4

14822: 14696: 14331: 13986: 13956: 13845: 13804: 12857:

Kawaler, S. D. (1997). "White Dwarf Stars". In Kawaler, S. D.; Novikov, I.; Srinivasan, G. (eds.).

7730:

Kawaler, S. D. (1997). "White Dwarf Stars". In Kawaler, S. D.; Novikov, I.; Srinivasan, G. (eds.).

5826: 5276: 5121: 4846: 4646: 4242: 2936:. This limit may increase if the white dwarf is rotating rapidly and nonuniformly. White dwarfs in 2683:, to attempt to detect them looking for the signatures of their interaction with the white dwarf's 2529: 2026:

light. It is thought to have a surface field of approximately 300 million gauss (30 kT).

1589: 1529: 1481: 1065: 736:

As Eddington pointed out in 1924, densities of this order implied that, according to the theory of

424: 392:

announced in 1915 that he had found the spectrum of Sirius B to be similar to that of Sirius.

356: 327: 12147:

Yoon, S.-C.; Langer, N. (2004). "Presupernova evolution of accreting white dwarfs with rotation".

6847:

The Moment of Creation: Big Bang Physics from Before the First Millisecond to the Present Universe

6001:"Stars, Distribution and Motions of, Note on equilibrium configurations for rotating white dwarfs" 3097:. As well as novae and dwarf novae, several other classes of these variables are known, including 2029:

Since 1970, magnetic fields have been discovered in well over 200 white dwarfs, ranging from

1080:

such collisions are the major source of supernovae. This hypothesis is based on the fact that the

15598: 15349: 15148: 15058: 15018: 15000: 14926: 14497: 14423: 13903: 13634: 12829:"Citizen Scientist Leads Discovery of 34 Ultracool Dwarf Binaries Using Archive at NSF's NOIRLab" 9869: 9357:

Woosley, S. E.; Heger, A.; Weaver, T. A. (2002). "The evolution and explosion of massive stars".

6343: 6128:

Chanillo, Sagun; Weiss, Georg S. (2012). "A remark on the geometry of uniformly rotating stars".

5266: 2907: 2823: 2655: 2315: 1972: 1759: 1326: 1277: 147: 10012:

Jura, M. (1 May 2008). "Pollution of Single White Dwarfs by Accretion of Many Small Asteroids".

5487: 1458:

becomes zero at a finite value of the mass. This is the limiting value of the mass – called the

388:

observed a previously unseen star close to Sirius, later identified as the predicted companion.

15924: 15759: 15739: 15511: 15506: 15404: 15299: 15248: 15053: 15043: 14716: 14514: 14482: 14373: 14356: 14250: 13835: 5563: 3629: 2973: 2965: 2334: 2311: 1930: 1919: 1285: 1036: 741: 448: 335: 219: 57: 2977:

response. Rather, the increased temperature accelerates the rate of the fusion reaction, in a

2373: 15919: 15613: 15583: 15578: 15568: 15496: 15284: 14450: 14225: 13881: 13767: 13748: 13667: 13511: 12670: 10751: 8363: 5669: 4948: 4293: 3678: 2467: 2085: 1911: 1032: 708: 403:, an isolated white dwarf. These three white dwarfs, the first discovered, are the so-called 14731: 12772: 12603: 12403: 12224: 12170: 11934:"On the orbits of low-mass companions to white dwarfs and the fates of the known exoplanets" 11552: 11526: 11487: 11461: 11177:"The critical binary star separation for a planetary system origin of white dwarf pollution" 9974: 9563: 9308: 8855: 8498: 8288: 7586: 7450: 7338: 7228: 7144: 6981: 5879: 5795: 2192:, stars, including HL Tau 76, with hydrogen-dominated atmospheres and the spectral type DA; 1259: 688:

White dwarfs were found to be extremely dense soon after their discovery. If a star is in a

15754: 15652: 15642: 15491: 15459: 15253: 15048: 15033: 14346: 14103: 14091: 13898: 13738: 13523: 13406: 13263: 13195: 13153: 13057: 13009: 12899: 12768: 12715: 12599: 12532: 12471: 12399: 12342: 12282: 12220: 12166: 12057: 11998: 11955: 11888: 11831: 11719: 11548: 11483: 11359: 11261: 11198: 11131: 11108:

Gänsicke, Boris T.; Holman, Matthew J.; Veras, Dimitri; Payne, Matthew J. (21 March 2016).

11064: 10997: 10930: 10865: 10818: 10771: 10718: 10626: 10586: 10549: 10490: 10433: 10369: 10318: 10281: 10232: 10162: 10105: 10031: 9970: 9824: 9771: 9711: 9654: 9606: 9559: 9512: 9465: 9366: 9304: 9257: 9218: 9151: 9112: 9056: 9003: 8947: 8904: 8851: 8804: 8765: 8727: 8602: 8547: 8494: 8439: 8382: 8333: 8284: 8249: 8155: 8110: 8059: 8009: 7948: 7893: 7844: 7805: 7768: 7693: 7655: 7582: 7506: 7446: 7391: 7334: 7273: 7236: 7224: 7187: 7140: 7055: 7008: 6977: 6942: 6897: 6807: 6758: 6698: 6651: 6607: 6566: 6525: 6482: 6433: 6376: 6293: 6252: 6200: 6147: 6094: 6053: 6012: 5973: 5875: 5791: 5717: 5673: 5641: 5595: 5524: 5394: 5357: 5311: 5231: 5166: 5093: 5044: 4997: 4921: 4874: 4809: 4754: 4703: 4655: 4609: 4563: 4520: 4474: 4430: 4384: 4338: 4302: 4260: 4211: 4175: 4117: 4065: 4011: 3922: 3880: 3794: 3601: 3094: 3025: 2788:

in age and probably also in their atmosphere. Confirmation will be possible via the common

2448: 2338: 2290: 2023: 1517: 1497: 1454: 400: 380:

Bessel roughly estimated the period of the companion of Sirius to be about half a century;

323: 279: 171: 13228: 12034:

Lopes de Oliveira, R.; Bruch, A.; Rodrigues, C. V.; de Oliveira, A. S.; Mukai, K. (2020).

11698:"JWST Directly Images Giant Planet Candidates Around Two Metal-Polluted White Dwarf Stars" 11460:

Kervella, Pierre; Arenou, Frédéric; Mignard, François; Thévenin, Frédéric (1 March 2019).

10469:"How Sublimation Delays the Onset of Dusty Debris Disk Formation around White Dwarf Stars" 7251: 4417:"The mean parallax of early-type stars of determined proper motion and apparent magnitude" 1072:

explosion in which the white dwarf may be destroyed, before it reaches the limiting mass.

8: 15904: 15876: 15214: 15197: 14868: 14770: 14593: 14076: 14054: 13936: 13830: 13547: 13443: 10598: 9068: 8361:

Ferrario, Lilia; de Martino, Domtilla; Gaensicke, Boris (2015). "Magnetic white dwarfs".

4320: 4193: 3006: 2990: 2863: 2557: 1763: 1682: 1460: 1068:

mass from a neighboring star undergo a runaway nuclear fusion reaction, which leads to a

1041: 938:, meant that a white dwarf could cool to zero temperature and still possess high energy. 389: 359:

used position measurements to determine that the stars Sirius (α Canis Majoris) and

348: 267: 227: 116: 15354: 13267: 13199: 13157: 13061: 13013: 12903: 12719: 12536: 12475: 12411: 12346: 12286: 12061: 12002: 11959: 11892: 11835: 11812:

Agol, Eric (2011). "Transit Surveys for Earths in the Habitable Zones of White Dwarfs".

11723: 11363: 11265: 11202: 11135: 11068: 11001: 10934: 10869: 10822: 10775: 10722: 10630: 10590: 10553: 10494: 10437: 10373: 10322: 10285: 10236: 10166: 10109: 10035: 9828: 9775: 9715: 9658: 9610: 9516: 9469: 9370: 9261: 9222: 9155: 9116: 9060: 9007: 8951: 8908: 8885:

O'Brien, M. S. (2000). "The Extent and Cause of the Pre–White Dwarf Instability Strip".

8808: 8769: 8731: 8606: 8551: 8443: 8386: 8337: 8253: 8159: 8114: 8072: 8063: 8047: 8013: 7952: 7897: 7848: 7809: 7772: 7697: 7659: 7510: 7395: 7277: 7191: 7098: 7059: 7012: 6946: 6901: 6811: 6762: 6702: 6655: 6611: 6570: 6529: 6486: 6437: 6380: 6297: 6256: 6204: 6151: 6098: 6057: 6016: 5721: 5645: 5599: 5528: 5398: 5361: 5315: 5235: 5170: 5097: 5048: 5001: 4987: 4925: 4878: 4813: 4758: 4707: 4659: 4613: 4567: 4524: 4478: 4434: 4388: 4342: 4306: 4264: 4215: 4179: 4121: 4069: 4015: 3926: 3884: 3798: 3000:

was the favored mechanism for Type Ia supernovae, but now, because of observations, the

1550:. This enables the composition and structure of their atmospheres to be studied by soft 15864: 15852: 15749: 15710: 15662: 15647: 15561: 15501: 15424: 15334: 15304: 15294: 15238: 15160: 14851: 14487: 14286: 14120: 14098: 13946: 13888: 13622: 13518: 13287: 13253: 13211: 13185: 13121: 13095: 13025: 12889: 12758: 12731: 12705: 12623: 12589: 12556: 12522: 12495: 12461: 12389: 12332: 12272: 12236: 12210: 12182: 12156: 12075: 12047: 11973: 11945: 11909: 11878: 11866: 11847: 11821: 11792: 11760: 11709: 11665: 11622: 11604: 11572: 11538: 11507: 11473: 11440: 11383: 11349: 11285: 11251: 11224: 11188: 11157: 11121: 11090: 11054: 11023: 10987: 10956: 10920: 10889: 10855: 10787: 10783: 10761: 10734: 10708: 10602: 10576: 10521: 10480: 10468: 10449: 10423: 10393: 10342: 10308: 10258: 10222: 10188: 10131: 10095: 10055: 10043: 10021: 9994: 9960: 9840: 9814: 9787: 9761: 9729: 9701: 9670: 9644: 9575: 9549: 9481: 9455: 9446:

Schaffner-Bielich, Jürgen (2005). "Strange quark matter in stars: A general overview".

9294: 9102: 9072: 9046: 9019: 8993: 8963: 8920: 8894: 8867: 8841: 8618: 8592: 8563: 8537: 8510: 8484: 8457: 8429: 8398: 8372: 8300: 8222: 8214: 8179: 8128: 8100: 8025: 7999: 7972: 7938: 7911: 7883: 7833: 7709: 7598: 7572: 7530: 7496: 7462: 7436: 7409: 7381: 7350: 7324: 7263: 7156: 7130: 7071: 7045: 6887: 6850: 6748: 6714: 6688: 6515: 6451: 6423: 6392: 6216: 6190: 6163: 6137: 6110: 5891: 5865: 5807: 5781: 5743: 5707: 5540: 5483: 5418: 5410: 5247: 5243: 5221: 5189: 5154: 5125: 5060: 5034: 4892: 4864: 4825: 4799: 4770: 4744: 4366: 4143: 4135: 4081: 4055: 4027: 4001: 3938: 3912: 3870: 3171: 3114: 3102: 2937: 2912: 2896: 2460: 2383: 1948: 1944: 1107:, whose cores are supported in part by thermal pressure, or the even lower-temperature 737: 611: 396: 385: 331: 285: 13021: 12966: 11843: 10877: 10299:

Farihi, J. (1 April 2016). "Circumstellar debris and pollution at white dwarf stars".

9666: 8959: 8021: 7370:"22 Ne Phase Separation as a Solution to the Ultramassive White Dwarf Cooling Anomaly" 1325:

is the speed of light, and it can be shown that there is no stable equilibrium in the

48: 15700: 15125: 15098: 15078: 14878: 14662: 14650: 14477: 14457: 14411: 14393: 14361: 14210: 14049: 13976: 13651: 13484: 13453: 13279: 13113: 13029: 12972: 12954: 12917: 12862: 12735: 12727: 12627: 12615: 12548: 12487: 12415: 12358: 12298: 12121: 12094: 12079: 12014: 11977: 11914: 11851: 11626: 11576: 11564: 11511: 11499: 11375: 11277: 11216: 11149: 11082: 11027: 11015: 10960: 10948: 10893: 10881: 10791: 10606: 10526: 10508: 10453: 10385: 10346: 10334: 10262: 10250: 10192: 10180: 10135: 10123: 10047: 9998: 9986: 9724: 9689: 9674: 9485: 9477: 9270: 9245: 9124: 8967: 8924: 8402: 8304: 8171: 8089:"The composition of a disrupted extrasolar planetesimal at SDSS J0845+2257 (Ton 345)" 8029: 7964: 7906: 7871: 7852: 7735: 7713: 7705: 7522: 7466: 7413: 7354: 7297: 7289: 7075: 6915: 6854: 6776: 6533: 6446: 6411: 6396: 6347: 6220: 5856:

Chabrier, G.; Baraffe, I. (2000). "Theory of low-Mass stars and substellar objects".

5733: 5702:

Canal, R.; Gutierrez, J. (1997). "The Possible White Dwarf-Neutron Star Connection".

5544: 5422: 5319: 5194: 5135: 5005: 4887: 4850: 4147: 3942: 3752: 3595: 2969: 2949: 2924: 2875: 2855: 2819: 2804: 2799:

system is polluted with calcium from rocky material. The white dwarf is orbited by a

2594: 2440: 2235: 1992: 1937:

The symbols "?" and ":" may also be used if the correct classification is uncertain.

1681:

into a solid state, starting at its center. The crystal structure is thought to be a

1656: 1619: 1449: 1077: 1069: 934: 905: 255: 244: 240: 123: 93: 15185: 13125: 12240: 11289: 11228: 11161: 10738: 10059: 9791: 9733: 9187: 9076: 9023: 8622: 8514: 8461: 8226: 8132: 7915: 7602: 7534: 6555:"The Chemical Evolution of Cool White Dwarfs and the Age of the Local Galactic Disk" 6455: 5895: 5811: 5251: 4896: 4829: 4774: 4085: 3959: 3708: 1983:

Magnetic fields in white dwarfs with a strength at the surface of c. 1 million

1766:. The envelope is believed to consist of a helium-rich layer with mass no more than 1419:{\displaystyle M_{\rm {limit}}\approx N^{2}\left({\frac {\hbar c}{G}}\right)^{3/2}.} 15828: 15528: 15481: 15431: 15419: 15397: 15392: 15319: 15279: 15226: 15008: 14931: 14906: 14800: 14721: 14445: 14406: 14022: 13924: 13698: 13291: 13271: 13215: 13203: 13161: 13109: 13105: 13065: 13017: 12907: 12723: 12607: 12560: 12540: 12499: 12479: 12407: 12350: 12290: 12228: 12186: 12174: 12065: 12006: 11963: 11904: 11896: 11839: 11770: 11727: 11614: 11556: 11491: 11387: 11367: 11269: 11206: 11139: 11094: 11072: 11005: 10938: 10873: 10826: 10779: 10726: 10594: 10516: 10498: 10441: 10397: 10377: 10326: 10240: 10170: 10113: 10039: 9978: 9921: 9844: 9832: 9779: 9719: 9662: 9614: 9579: 9567: 9520: 9473: 9374: 9265: 9226: 9159: 9120: 9064: 9011: 8955: 8912: 8871: 8859: 8812: 8773: 8735: 8647: 8642: 8610: 8583: 8567: 8555: 8502: 8447: 8390: 8341: 8292: 8257: 8206: 8183: 8163: 8118: 8067: 8017: 7976: 7956: 7901: 7813: 7776: 7701: 7590: 7514: 7482:"Core crystallization and pile-up in the cooling sequence of evolving white dwarfs" 7454: 7399: 7342: 7281: 7232: 7195: 7160: 7148: 7063: 7016: 6950: 6905: 6825: 6815: 6766: 6718: 6706: 6659: 6615: 6574: 6490: 6441: 6384: 6301: 6260: 6208: 6155: 6114: 6102: 6061: 6020: 5887: 5883: 5803: 5799: 5747: 5725: 5649: 5603: 5532: 5512: 5402: 5365: 5239: 5184: 5174: 5101: 5064: 5052: 4929: 4882: 4817: 4762: 4711: 4663: 4617: 4571: 4528: 4482: 4438: 4392: 4346: 4268: 4219: 4125: 4099: 4073: 4031: 4019: 3930: 3802: 3617: 3547:

Artist's impression of an evolving white dwarf and millisecond pulsar binary system

3195: 3050:

instead of a red dwarf). These binaries form when the red dwarf is engulfed in the

2712: 2586: 2549: 2513: 2298: 2223: 2218:

between the asymptotic giant branch and the white dwarf region. They may be called

1996: 1686: 1666: 1614: 1513: 1049: 958: 954: 896:. There is therefore no obstacle to placing nuclei closer than normally allowed by 885: 802: 724: 712: 420: 319: 179: 12980: 12611: 11867:"Habitable Planets Around White and Brown Dwarfs: The Perils of a Cooling Primary" 11618: 11560: 11495: 10677: 9982: 9891: 8863: 8506: 7594: 7458: 7346: 6212: 6167: 5443: 2811:

are being disrupted by the brown dwarf, causing the pollution of the white dwarf.

2060:

The magnetic fields in a white dwarf may allow for the existence of a new type of

1933:

lines which also had hydrogen features could be given the classification of DBAP3.

1329:. In particular, this analysis yields the maximum mass of a white dwarf, which is 15715: 15518: 15387: 15231: 15202: 15143: 15138: 15013: 14741: 14706: 14640: 14586: 14581: 14526: 14336: 13941: 13931: 13893: 13552: 12232: 12178: 12010: 10278:

Recognition of the First Observational Evidence of an Extrasolar Planetary System

9864: 9571: 7152: 6082: 5970: 5131: 3746: 3562: 3138: 3134: 3055: 2978: 2744:

is the first and only transiting major planet around a white dwarf (as of 2022).

2561: 2544:

and magnesium in its atmosphere, but van Maanen misclassified it as the faintest

2500: 2470:. The resultant object, orbiting the former companion, now host star, could be a 2456: 2121: 2001: 1754: 1551: 1101: 1086: 590: 32: 12354: 11749:"PHL 5038AB: Is the brown dwarf causing pollution of its white dwarf host star?" 10330: 5936: 5729: 419:

when he examined this class of stars in 1922; the term was later popularized by

15888: 15816: 15777: 15543: 15382: 15209: 15180: 15155: 15088: 14777: 14645: 14531: 14433: 14323: 14313: 13961: 13951: 13602: 12828: 12807: 12786: 12070: 12035: 11732: 11697: 10503: 10245: 10210: 10118: 10083: 10079: 9378: 8687: 7404: 7369: 7285: 7176:"Asteroseismology of the Crystallized ZZ Ceti Star BPM 37093: A Different View" 6910: 6875: 6339: 5910: 5772:

Hillebrandt, W.; Niemeyer, J. C. (2000). "Type IA supernova explosion models".

3090: 3078: 2942: 2879: 2859: 2851: 2708: 2684: 2509: 2436: 2172:

Early calculations suggested that there might be white dwarfs whose luminosity

1926: 1907: 1750: 1734: 1670: 1485: 1306: 897: 889: 597: 13991: 12451: 11175:

Rebassa-Mansergas, Alberto; Xu (许偲艺), Siyi; Veras, Dimitri (21 January 2018).

10804: 9783: 8652: 8394: 7518: 6495: 6470: 6159: 6025: 6000: 5155:"The Relativity Displacement of the Spectral Lines in the Companion of Sirius" 4273: 4246: 1962: 15898: 15729: 15523: 15486: 15454: 15329: 15038: 14861: 14832: 14810: 14428: 14401: 14378: 14279: 14151: 14146: 14115: 13876: 13861: 13641: 13585: 13557: 13463: 12921: 12619: 12419: 12362: 12302: 11990: 11568: 11503: 11281: 11220: 11153: 11086: 11019: 10976:"Eccentric planets and stellar evolution as a cause of polluted white dwarfs" 10952: 10885: 10512: 10389: 10338: 10254: 10184: 10127: 10051: 9990: 9327: 8261: 7293: 6919: 6780: 6771: 6736: 5654: 5629: 5370: 5345: 4637: 4622: 4597: 4502: 4458: 4412: 3704: 2982: 2789: 2475: 2471: 2173: 2073: 2061: 2006: 1703: 1627: 1512:

The degenerate matter that makes up the bulk of a white dwarf has a very low

1253: 1008:

equal to 2 for such a star, leading to the commonly quoted value of 1.4

996: 992: 913: 881: 831: 546: 412: 408: 384:

computed an orbit for it in 1851. It was not until 31 January 1862 that

309: 293: 151: 12951:

Black holes, white dwarfs, and neutron stars: the physics of compact objects

12912: 12877: 11775: 11748: 11211: 11176: 11144: 11109: 10943: 10908: 8686:. Association Française des Observateurs d'Etoiles Variables. Archived from 8614: 8146:

Blackett, P. M. S. (1947). "The Magnetic Field of Massive Rotating Bodies".

8123: 8088: 7021: 6997:"The Status of White Dwarf Asteroseismology and a Glimpse of the Road Ahead" 6996: 1741:

Although most white dwarfs are thought to be composed of carbon and oxygen,

1532:, luminosity increases with increasing surface temperature (proportional to 876:

Such densities are possible because white dwarf material is not composed of

716: 15840: 15789: 15464: 15414: 15409: 15309: 15192: 15175: 15133: 15103: 15093: 15028: 14911: 14856: 14837: 14817: 14795: 14787: 14630: 14623: 14462: 14383: 14366: 14027: 14001: 13871: 13866: 13790: 13672: 13646: 13629: 13580: 13530: 13496: 13448: 13283: 13117: 12552: 12491: 11968: 11933: 11918: 11379: 11077: 11042: 11010: 10975: 10530: 10211:"Discovery of Beryllium in White Dwarfs Polluted by Planetesimal Accretion" 8452: 8417: 8210: 8175: 7968: 7616: 7526: 7301: 6737:"Spectral analysis of ultra-cool white dwarfs polluted by planetary debris" 6640:"The Cool White Dwarf Luminosity Function and the Age of the Galactic Disk" 6471:"On the theory of white dwarf stars. I. The energy sources of white dwarfs" 5406: 5271: 5198: 4130: 4103: 4045: 3612: 3606: 3439: 3282: 3098: 3010: 2808: 2785: 2741: 2723: 2700: 2692: 2676: 2659: 2578: 2537: 2452: 2323: 2202: 2181: 1988: 1984: 1966:

Elements discovered in the atmosphere of white dwarfs colder than 25,000 K.

1903: 1742: 1566: 1555: 1061: 922: 901: 674: 670: 658: 583: 511: 504: 497: 490: 483: 476: 469: 462: 455: 315: 305: 297: 131: 100:; no fusion takes place in a white dwarf. The nearest known white dwarf is 69: 13381: 13367: 13353: 13339: 13325: 13311: 12576:"Deep and fast Solar System flybys: The controversial case of WD 0810-353" 12033: 11900: 5179: 1902:

The first attempt to classify white dwarf spectra appears to have been by

1428: 1245:

is the number of electrons per unit mass (dependent only on composition),

629:

Although white dwarfs are known with estimated masses as low as 0.17

15705: 15377: 15369: 15359: 15339: 15314: 15243: 15165: 14921: 14896: 14891: 14765: 14726: 14674: 14669: 14341: 14071: 14037: 13966: 13612: 13540: 13479: 13190: 13100: 12763: 12215: 12161: 11525:

Kervella, Pierre; Arenou, Frédéric; Thévenin, Frédéric (1 January 2022).

11043:"Unstable low-mass planetary systems as drivers of white dwarf pollution" 10713: 10428: 9766: 9706: 9554: 9460: 9299: 8998: 8899: 8846: 8542: 7888: 7135: 7050: 6693: 6520: 6428: 5870: 5786: 5712: 5706:. Astrophysics and Space Science Library. Vol. 214. pp. 49–55. 5473: 5226: 5039: 4869: 4804: 4749: 4060: 4006: 3917: 3875: 3584: 3578: 3470: 3047: 3029: 2871: 2800: 2735: 2731: 2545: 2525: 2520: 2378: 2200:, stars, with helium-dominated atmospheres and the spectral type DB; and 2019: 2018:) which was identified by James Kemp, John Swedlund, John Landstreet and 1929:, an effective temperature of 17,000 K, and a spectrum dominated by 1698: 1678: 1632: 1585: 1108: 689: 518: 334:

discovered that, despite being a dim star, 40 Eridani B was of

301: 259: 108: 13275: 12544: 12483: 11589: 11371: 10909:"Detectable close-in planets around white dwarfs through late unpacking" 9231:

10.1002/1521-3994(200112)322:5/6<405::AID-ASNA405>3.0.CO;2-6

7960: 7646:

Schatzman, E. (1945). "Théorie du débit d'énergie des naines blanches".

6830: 6334:

Fontaine, G.; Wesemael, F. (2001). "White dwarfs". In Murdin, P. (ed.).

4989:

Preliminary General Catalogue of 6188 stars for the epoch 1900

2730:

data. The brightening is not seen before 2018. It is interpreted as the

2052:

in which the compact object is a white dwarf instead of a neutron star.

1954:) has been detected in spectra of the atmospheres of some white dwarfs. 657:. The estimated radii of observed white dwarfs are typically 0.8–2% the 15289: 14986: 14959: 14936: 14916: 14901: 14753: 14657: 14635: 14613: 14608: 14472: 14215: 14130: 14110: 14081: 14032: 13981: 13592: 13535: 12878:"New white dwarf stars in the Sloan Digital Sky Survey Data Release 10" 8296: 6388: 6106: 5536: 5414: 3376: 3344: 3313: 3181: 3162: 3082: 2915:, causing their mutual orbit to steadily shrink until the stars merge. 2834: 2796: 2751: 2439:

star or a super-Chandrasekhar mass white dwarf which will explode in a

2415: 2319: 2254: 2253:

If the mass of a main-sequence star is lower than approximately half a

2069: 2045: 1791: 1663: 1521: 1493: 1468:

in hydrostatic equilibrium. The average molecular weight per electron,

1093: 682: 678: 604: 576: 562: 289: 231: 191: 187: 135: 89: 15883: 12573: 10280:. 19Th European Workshop on White Dwarfs. Vol. 493. p. 291. 8218: 7796:

Luyten, W. J. (1952). "The Spectra and Luminosities of White Dwarfs".

5630:"The highly collapsed configurations of a stellar mass (Second paper)" 4139: 3869:. 14th European Workshop on White Dwarfs. Vol. 334. p. 165. 2663:

from its AGB progenitor about 500 million years ago) white dwarf

1636:

in approximate thermal equilibrium with its surroundings and with the

347:

The spectral type of 40 Eridani B was officially described in 1914 by

15476: 15324: 15108: 15073: 15068: 15063: 15023: 14976: 14966: 14760: 14736: 14711: 14618: 14569: 14502: 14492: 14467: 14440: 14416: 14351: 14061: 14044: 13597: 12695: 10381: 9423:. lecture notes, Physics 213. University of Sheffield. Archived from 9396:. lecture notes, Physics 213. University of Sheffield. Archived from 8167: 5307: 4507:"Additional note on faint early-type stars with large proper motions" 3865:

Werner, K.; Hammer, N.J.; Nagel, T.; Rauch, T.; Dreizler, S. (2005).

3130: 3051: 2755: 2533: 2350: 2346: 2177: 1694: 1577: 1489: 1465: 1224:{\displaystyle R\approx {\frac {N^{5/3}\hbar ^{2}}{2m_{e}GM^{1/3}}},} 1130: 1104: 1039:

for this and other work in 1983. The limiting mass is now called the

928: 569: 532: 312: 204: 155: 139: 27:

Type of stellar remnant composed mostly of electron-degenerate matter

12294: 11992: 9037:

Napiwotzki, Ralf (2009). "The galactic population of white dwarfs".

8318:

Kemp, J.C.; Swedlund, J.B.; Landstreet, J.D.; Angel, J.R.P. (1970).

5974:"The Structure, Stability, and Dynamics of Self-Gravitating Systems" 3113:

Other non-pre-supernova binaries include binaries that consist of a

2814:

In 2024 a planet candidate was found around the massive white dwarf

2261:, and end its evolution as a helium white dwarf composed chiefly of 436: 15469: 15170: 14844: 14603: 14576: 14066: 13825: 13506: 13207: 13166: 13141: 13070: 13045: 12594: 12119: 12092: 12052: 11797: 11765: 11714: 11609: 11543: 11478: 11445: 11354: 11273: 11193: 11126: 11059: 10831: 10806: 10730: 10485: 10445: 10313: 10227: 10175: 10150: 10100: 9836: 9619: 9594: 9525: 9500: 9246:"The formation of helium white dwarfs in close binary systems – II" 9164: 9139: 9015: 8916: 8817: 8792: 8777: 8740: 8715: 8597: 8559: 8377: 8346: 8319: 8105: 7817: 7781: 7756: 7684:

Koester, D.; Chanmugam, G. (1990). "Physics of white dwarf stars".

7501: 7441: 7386: 7268: 7200: 7175: 7067: 6954: 6933:

van Horn, H. M. (January 1968). "Crystallization of White Dwarfs".

6892: 6820: 6795: 6753: 6710: 6664: 6639: 6620: 6595: 6579: 6554: 6367:

Heise, J. (1985). "X-ray emission from isolated hot white dwarfs".

6306: 6281: 6265: 6240: 6195: 6066: 6041: 5608: 5583: 5106: 5079: 5056: 4933: 4821: 4766: 4716: 4691: 4668: 4641: 4576: 4549: 4533: 4506: 4487: 4462: 4443: 4416: 4397: 4370: 4351: 4324: 4224: 4197: 4077: 4023: 3934: 3807: 3780: 3638: – Chronological list of developments in knowledge and records 3532: 3408: 3129:

around white dwarfs. While stars are bright and often outshine the

3122: 3017:

slows until the spin is no longer enough to prevent the explosion.

2672: 2556:

in white dwarfs is thought to come from nitrogen-ice of extrasolar

2553: 2424: 2262: 1674: 1605: 1569:. This process has more effect on hotter and younger white dwarfs. 1562: 1053: 893: 555: 539: 266:, which establishes an observational limit on the maximum possible 143: 102: 13258: 12953:, Stuart L. Shapiro and Saul A. Teukolsky, New York: Wiley, 1983. 12894: 12710: 12527: 12466: 12394: 12337: 12277: 11950: 11883: 11826: 11400: 11256: 10992: 10925: 10860: 10766: 10581: 10026: 9965: 9819: 9804: 9649: 9107: 9051: 8489: 8434: 8004: 7943: 7577: 7329: 6142: 4598:"On the relation between the masses and luminosities of the stars" 2948:

There are two models that might explain the progenitor systems of

2341:. Such a star may leave a remnant white dwarf composed chiefly of 338: A, or white. In 1939, Russell looked back on the discovery: 199:), the core temperature will be sufficient to fuse carbon but not 15744: 15219: 14981: 14748: 14701: 14684: 14679: 14598: 13919: 12644:. fact sheet. Imagine the Universe!. NASA Goddard. Archived from 11338: 7368:

Blouin, Simon; Daligault, Jérôme; Saumon, Didier (1 April 2021).

3250: 3021: 2867: 2727: 2716: 2688: 2573: 2565: 2541: 1057: 753: 360: 248: 175: 77: 13140:

Provencal, J. L.; Shipman, H. L.; Hog, Erik; Thejll, P. (1998).

13086:

Gibson, B. K.; Flynn, C (2001). "White Dwarfs and Dark Matter".

8474: 6876:"On the Nature of Ultracool White Dwarfs: Not so Cool after All" 5139: 5009: 2293:, but it will never become sufficiently hot to fuse carbon into 1651: 744:. This was confirmed when Adams measured this redshift in 1925. 15734: 15722: 14941: 14827: 13809: 13759: 13501: 12574:

de la Fuente Marcos, Raúl; de la Fuente Marcos, Carlos (2022).

12376:

Maoz, Dan; Mannucci, Filippo; Nelemans, Gijs (18 August 2014).

8938:

Winget, D. E. (1998). "Asteroseismology of white dwarf stars".

7856: 7314: 6796:"An independent method for determining the age of the universe" 6282:"WD 0346+246: A Very Low Luminosity, Cool Degenerate in Taurus" 6238: 5944: 4787: 4733: 4463:"Note on some faint early-type stars with large proper motions" 4247:"On the variations of the proper motions of Procyon and Sirius" 3900: 3218: 2664: 2444: 2428: 2427:

continues to expand, it is thought that in 10 to 10 years, the

2342: 2286: 2282: 2238:

for main-sequence stars with masses from about 0.07 to 10

2140: 2049: 2011: 1746: 1594: 793: 700:, which compares well with a more modern estimate of 1.00 407:. Eventually, many faint white stars were found which had high 263: 167: 163: 159: 53: 13398: 13000:

Winget, D.E. (1998). "Asteroseismology of white dwarf stars".

12378:"Observational Clues to the Progenitors of Type Ia Supernovae" 12261:"Type-Ia Supernova Rates and the Progenitor Problem: A Review" 12199: 12095:"Astronomers Discover Merging Star Systems that Might Explode" 11174: 7215:

Hansen, B. M. S.; Liebert, James (2003). "Cool White Dwarfs".

2274:

If the mass of a main-sequence star is between 0.5 and 8

1572: 13142:"Testing the White Dwarf Mass-Radius Relation with Hipparcos" 11694: 11459: 10645:"The MIRI survey for Exoplanets Orbiting White-dwarfs (MEOW)" 10619: 10413: 10077: 7562: 7479: 2754:

are suspected to have giant exoplanets due to anomaly in the

2680: 2668: 2184:

pulsations. Known types of pulsating white dwarf include the

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If a white dwarf were to exceed the Chandrasekhar limit, and

666: 107:

at 8.6 light years, the smaller component of the Sirius

85: 12875: 9633: 8418:"Magnetic white dwarf stars in the Sloan Digital Sky Survey" 8415: 8320:"Discovery of circularly polarized light from a white dwarf" 5515:(1929). "Über die Grenzdichte der Materie und der Energie". 3632: – Classification of stars based on spectral properties 2895:

The merger process of two co-orbiting white dwarfs produces

2765:

A JWST survey of four metal polluted white dwarfs found two

2281:, its core will become sufficiently hot to fuse helium into 15083: 14302: 13575: 13243: 12808:"Cosmic 'Spider' Found to Be Source of Powerful Gamma-Rays" 12748: 11040: 10805:

Li, Jianke; Ferrario, Lilia; Wickramasinghe, Dayal (1998).

10466: 8360: 8317: 8274: 8086: 7928: 7426: 6793: 6734: 6241:"A proposed new white dwarf spectral classification system" 3620: – Type of emission nebula created by dying red giants 2903: 2488:

List of exoplanets and planetary debris around white dwarfs

2432: 2387: 2362: 2294: 877: 200: 127: 97: 31:"Degenerate dwarf" redirects here. Not to be confused with 15835: 15784: 12093:

Aguilar, David A.; Pulliam, Christine (16 November 2010).

9892:"Hubble finds dead stars "polluted" with planetary debris" 8580: 7869: 6596:"A Catalogue of Spectroscopically Identified White Dwarfs" 5827:"From the Clash of White Dwarfs, the Birth of a Supernova" 4845: 15449: 13139: 12981:"Estimating Stellar Parameters from Energy Equipartition" 11669: 10208: 6873: 6409: 5444:"Estimating Stellar Parameters from Energy Equipartition" 5022: 4109:

Philosophical Transactions of the Royal Society of London

3207: 723:'s, which was so high that he called it "impossible". As 720: 186:). If the mass of the progenitor is between 7 and 9 154:

of low or medium mass ends, such a star will expand to a

81: 14271: 11746: 11107: 9137: 7252:"Buoyant crystals halt the cooling of white dwarf stars" 7035: 6412:"A two-stream formalism for the convective Urca process" 4692:"A catalog of spectroscopically identified white dwarfs" 3778: 2945:

in the white dwarf or its collapse into a neutron star.

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Timeline of white dwarfs, neutron stars, and supernovae

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Timeline of white dwarfs, neutron stars, and supernovae

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