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Neutron Stars and White Dwarfs

When stars die, their fate is determined by how massive they were in life. Stars like our Sun leave behind white dwarfs: Earth-size remnants of the original star’s core. More massive stars explode as supernovas, while their cores collapse into neutron stars: ultra-dense, fast-spinning spheres made of the same ingredients as the nucleus of an atom. At least some neutron stars are pulsars, which produce powerful beams of light, which as they sweep across our view from Earth look like extremely regular flashes.

Small as they are, the deaths of these compact objects change the chemistry of the universe. The supernova explosions of white dwarfs and the collisions of neutron stars create new elements on the periodic table. For all these reasons, white dwarfs and neutron stars are important laboratories for physics at the extremes of strong gravity, density, and temperature.

Center for Astrophysics | Harvard & Smithsonian scientists study many different aspects of white dwarfs and neutron stars:

Observing the way white dwarfs interact with other astronomical objects, including stars and planets. White dwarfs produce a great deal of radiation, which can profoundly impact any nearby object. Cosmic ‘Death Star’ is Destroying a Planet

Studying type Ia supernovas and the remnants of the explosions using many types of light. Astronomers are still trying to figure out whether most supernovas of this type are caused by two white dwarfs or a white dwarf in mutual orbit with an ordinary star. First Discovery of a Binary Companion for a Type Ia Supernova

Monitoring binary systems containing two white dwarfs in very close orbits. These systems are radiating gravitational waves that aren’t detectable by LIGO, but which astronomers measure indirectly by how the white dwarfs are increasing in speed. These systems will be very important for the upcoming Laser Interferometer Space Antenna (LISA), a joint NASA-ESA space-based gravitational wave observatory. One white dwarf binary, which orbits once every 12.75 minutes, will be potentially the “brightest” gravitational wave source for LISA. Space-Warping White Dwarfs Produce Gravitational Waves

Using NASA’s Chandra X-ray Observatory and other telescopes to find X-ray sources created by neutron stars in binary systems with ordinary stars. Additionally, some neutron stars, known as X-ray pulsars, are strong X-ray sources in and of themselves. NASA's Chandra Sees Runaway Pulsar Firing an Extraordinary Jet

Colliding neutron stars produce both gravitational waves detectable by LIGO and X-rays that can be observed with Chandra. These two types of observations provide complementary information and reveal much more than either could do alone. NASA Missions Catch First Light from a Gravitational-Wave Event

Using the Smithsonian’s Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory to study high-energy radiation emitted by pulsars in binary systems, to understand why their spin rate changes over time. Crab Pulsar Dazzles Astronomers with its Gamma-Ray Beams

White Dwarfs: Small and Mighty

Our Sun is a middle-aged star. It’s been around for roughly 5 billion years, and has about 5 billion more years to go before it dies. The lifespan of the Sun, like any other star, is determined by its mass, which in turn dictates how quickly it burns through its nuclear fuel . Once that fuel is exhausted, the Sun and other stars in the same mass range will shed their outermost layers, exposing the core. The remnant of that core, which are made mostly of carbon and oxygen, is a white dwarf roughly the diameter of Earth, but far more massive. Some white dwarfs are also created in binary systems, where the gravity from a companion object strips the outer layers of the star off, exposing the core. These white dwarfs are made of helium.

Despite their name, white dwarfs can range in color from blue-white to yellow, depending on how hot they are. They are common: most stars will eventually become white dwarfs. However, their small size makes them difficult to see directly unless they’re relatively close the Solar System. In many cases, though, they are in binary systems with ordinary stars, in which case astronomers can detect their presence by the gravitational effect they have on their companion.

Sometimes those white dwarf binary systems can end catastrophically. White dwarfs have a maximum mass of about 1.4 times the Sun’s mass, known as the Chandrasekhar limit. Beyond that point, adding mass can cause it to explode in a white dwarf supernova, also known as a “type Ia” supernova.

In binary systems, gravitational interactions between white dwarfs and a companion ordinary star can result in mass overflowing from the star onto the white dwarf. If enough mass flows onto the white dwarf to exceed the Chandrasekhar limit, the white dwarf goes supernova. Type Ia supernovas can also happen if two white dwarfs in a binary collide. This type of binary will be an important target for future gravitational wave detectors, though they don’t produce the right type of waves for current instruments like LIGO.

Whether the cause of the explosion is a normal star or another white dwarf, type Ia supernovas explode in very similar ways, producing a predictable pattern of light emission. Astronomers use that pattern to determine the distance to far-off galaxies, and refer to type Ia supernovas as “standard candles”.

This X-ray image shows the cloud of gas surrounding a young pulsar known as PSR B1509-58. The pulsar itself is only about 20 kilometers across, but its powerful emissions shape the environment around it.

The Life and Death of a Neutron Star

If a star is more than eight times the mass of the Sun, it burns through its nuclear fuel at a faster rate. However, the core shrinks and grows hotter as it consumes the fuel, letting it fuse heavier elements up to iron. Finally, when it can’t burn any more, the core collapses, and the star explodes in a supernova. If the star is heavier than about 20 times the Sun’s mass, the core becomes a black hole. In the range between 8 and 20 times the Sun’s mass, the remaining collapsed core gives birth to a neutron star.

These objects are more massive than the Sun, but only about 20 kilometers in diameter. The exterior is a crust made primarily of iron atoms. Beneath the surface, no atoms exist. Instead, electrons are smashed into protons to make neutrons. Deeper still, the neutron star consists of a fluid of protons and electrons, which flow without friction and produce powerful magnetic fields. The combination of intense gravity, high temperature, and extreme density makes neutron stars like nothing we can produce on Earth.

The magnetic fields channel matter surrounding the neutron star into light-emitting jets, much like those we see near some black holes. Neutron stars spin very rapidly, so if the jets pass across the field of view of our telescopes, we call them “pulsars” due to the flashes of light we observe. Most known neutron stars are pulsars.

Pulsars spin anywhere between once every few seconds to hundreds or — in the case of millisecond pulsars — thousands of times per second, depending on their environment and how they formed. Some millisecond pulsars spin so precisely they can be used as interstellar clocks. Astronomers study the different types of pulsars to understand why they spin at the rates they do, and how they change those rates during the neutron starquakes called “glitches”.

Like white dwarfs, some neutron stars are in binaries with other neutron stars, or partnered with ordinary stars. Colliding neutron star binaries are a significant source of gravitational waves, and produce explosions known as “kilonovas” or short-duration gamma-ray bursts. These events are powerful enough to start nuclear fusion reactions, producing elements like gold. Meanwhile, neutron stars that strip matter off companion stars produce bright X-ray and radio emissions.

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For the First Time Hubble Directly Measures Mass of a Lone White Dwarf

Astronomers using NASA's Hubble Space Telescope have for the first time directly measured the mass of a single, isolated white dwarf – the surviving core of a burned-out, Sun-like star.

Researchers found that the white dwarf is 56 percent the mass of our Sun. This agrees with earlier theoretical predictions of the white dwarf's mass and corroborates current theories of how white dwarfs evolve as the end product of a typical star's evolution. The unique observation yields insights into theories of the structure and composition of white dwarfs.

Until now, previous white dwarf mass measurements have been gleaned from observing white dwarfs in binary star systems. By watching the motion of two co-orbiting stars, straightforward Newtonian physics can be used to measure their masses. However, these measurements can be uncertain if the white dwarf's companion star is in a long-period orbit of hundreds or thousands of years. Orbital motion can be measured by telescopes only over a brief slice of the dwarf's orbital motion.

For this companion-less white dwarf, researchers had to employ a trick of nature, called gravitational microlensing. The light from a background star was slightly deflected by the gravitational warping of space by the foreground dwarf star. As the white dwarf passed in front of the background star, microlensing caused the star to appear temporarily offset from its actual position on the sky.

The results are reported in the Monthly Notices of the Royal Astronomical Society . The lead author is Peter McGill, formerly of the University of Cambridge (now based at the University of California, Santa Cruz).

These events are rare, and the effects are tiny. For instance, the size of our measured offset is like measuring the length of a car on the Moon as seen from Earth.

Peter McGill

McGill used Hubble to precisely measure how light from a distant star bent around the white dwarf, known as LAWD 37, causing the background star to temporarily change its apparent position in the sky.

Kailash Sahu of the Space Telescope Science Institute in Baltimore, Maryland, the principal Hubble investigator on this latest observation, first used microlensing in 2017 to measure the mass of another white dwarf, Stein 2051 B . But that dwarf is in a widely separated binary system. "Our latest observation provides a new benchmark because LAWD 37 is all by itself," Sahu said.

The collapsed remains of a star that burned out 1 billion years ago, LAWD 37 has been extensively studied because it is only 15 light-years away in the constellation Musca. "Because this white dwarf is relatively close to us, we’ve got lots of data on it – we've got information about its spectrum of light, but the missing piece of the puzzle has been a measurement of its mass," said McGill.

The team zeroed in on the white dwarf thanks to ESA's Gaia space observatory, which makes extraordinarily precise measurements of nearly 2 billion star positions. Multiple Gaia observations can be used to track a star's motion. Based on this data, astronomers were able to predict that LAWD 37 would briefly pass in front of a background star in November 2019.

Once this was known, Hubble was used to precisely measure over several years how the background star's apparent position in the sky was temporarily deflected during the white dwarf's passage.

"These events are rare, and the effects are tiny," said McGill. "For instance, the size of our measured offset is like measuring the length of a car on the Moon as seen from Earth."

Since the light from the background star was so faint, the main challenge for astronomers was extracting its image from the glare of the white dwarf, which is 400 times brighter than the background star. Only Hubble can make these kinds of high-contrast observations in visible light.

"The precision of LAWD 37's mass measurement allows us to test the mass-radius relationship for white dwarfs," said McGill. "This means testing the theory of degenerate matter (a gas so super-compressed under gravity it behaves more like solid matter) under the extreme conditions inside this dead star," he added.

The researchers say their results open the door for future event predictions with Gaia data. In addition to Hubble, these alignments can now be detected with NASA's James Webb Space Telescope. Because Webb works at infrared wavelengths, the blue glow of a foreground white dwarf looks dimmer in infrared light, and the background star looks brighter.

Based on Gaia's predictive powers, Sahu is observing another white dwarf, LAWD 66, with NASA's James Webb Space Telescope. The first observation was done in 2022. More observations will be taken as the deflection peaks in 2024 and then subsides.

"Gaia has really changed the game – it's exciting to be able to use Gaia data to predict when events will happen, and then observe them happening," said McGill. "We want to continue measuring the gravitational microlensing effect and obtain mass measurements for many more types of stars."

In his 1915 theory of general relativity, Einstein predicted that when a massive compact object passes in front of a background star, the light from the star would bend around the foreground object due to the warping of space by its gravitational field.

Exactly a century before this latest Hubble observation, in 1919, two British-organized expeditions to the southern hemisphere first detected this lensing effect during a solar eclipse on May 19th. It was hailed as the first experimental proof of general relativity – that gravity warps space. However, Einstein was pessimistic that the effect could ever be detected for stars outside our solar system because of the precision involved. "Our measurement is 625 times smaller than the effect measured at the 1919 solar eclipse," said McGill.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Media Contacts: Claire Andreoli NASA's Goddard Space Flight Center , Greenbelt, MD [email protected]

Ray Villard Space Telescope Science Institute, Baltimore, MD

Science Contacts:

Peter McGill University of California, Santa Cruz, Santa Cruz, CA Institute of Astronomy–University of Cambridge, Cambridge, United Kingdom

Kailash Sahu Space Telescope Science Institute, Baltimore, MD

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• Published: 15 June 2023

A 5.3-min-period pulsing white dwarf in a binary detected from radio to X-rays

• Ingrid Pelisoli   ORCID: orcid.org/0000-0003-4615-6556 1 ,
• T. R. Marsh 1 ,
• David A. H. Buckley   ORCID: orcid.org/0000-0002-7004-9956 2 , 3 , 4 ,
• I. Heywood   ORCID: orcid.org/0000-0001-6864-5057 5 , 6 , 7 ,
• Stephen. B. Potter 2 , 8 ,
• Axel Schwope 9 ,
• Jaco Brink   ORCID: orcid.org/0000-0003-0030-7566 2 , 3 ,
• Annie Standke 9 , 10 ,
• P. A. Woudt 3 ,
• S. G. Parsons   ORCID: orcid.org/0000-0002-2695-2654 11 ,
• M. J. Green 12 ,
• S. O. Kepler   ORCID: orcid.org/0000-0002-7470-5703 13 ,
• James Munday 1 , 14 ,
• A. D. Romero 13 ,
• E. Breedt   ORCID: orcid.org/0000-0001-6180-3438 15 ,
• A. J. Brown   ORCID: orcid.org/0000-0002-3316-7240 11 ,
• V. S. Dhillon   ORCID: orcid.org/0000-0003-4236-9642 11 , 16 ,
• M. J. Dyer   ORCID: orcid.org/0000-0003-3665-5482 11 ,
• P. Kerry 11 ,
• S. P. Littlefair 11 ,
• D. I. Sahman   ORCID: orcid.org/0000-0002-0403-1547 11 &
• J. F. Wild 11  

Nature Astronomy volume  7 ,  pages 931–942 ( 2023 ) Cite this article

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• Astrophysical magnetic fields
• Compact astrophysical objects
• Stellar evolution
• Time-domain astronomy

White dwarf stars are the most common stellar fossils. When in binaries, they make up the dominant form of compact object binary within the Galaxy and can offer insight into different aspects of binary formation and evolution. One of the most remarkable white dwarf binary systems identified to date is AR Scorpii (AR Sco). AR Sco is composed of an M dwarf star and a rapidly spinning white dwarf in a 3.56 h orbit. It shows pulsed emission with a period of 1.97 min over a broad range of wavelengths, which led to it being known as a white dwarf pulsar. Both the pulse mechanism and the evolutionary origin of AR Sco provide challenges to theoretical models. Here we report the discovery of a sibling of AR Sco, J191213.72-441045.1, which harbours a white dwarf in a 4.03 h orbit with an M dwarf and exhibits pulsed emission with a period of 5.30 min. This discovery establishes binary white dwarf pulsars as a class and provides support for proposed formation models for white dwarf pulsars.

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A pulsating white dwarf in an eclipsing binary

A binary pulsar in a 53-minute orbit

Data availability.

The TESS data used in this work are public and can be accessed via the Barbara A. Mikulski Archive for Space Telescopes ( https://mast.stsci.edu/ ). ULTRACAM and X-shooter data are made available in a Zenodo repository ( https://doi.org/10.5281/zenodo.7875811 ). Other data will become public in the respective telescope repositories after the proprietary time expires, but can be made available for analysis upon request to the corresponding author.

Code availability

Any of the custom data analysis scripts used in this work can be made available upon reasonable request to the corresponding author. This research made extensive use of Astropy ( http://www.astropy.org ), a community-developed core Python package for astronomy 75 , 76 .

Stanway, E. R. et al. VLA radio observations of AR Scorpii. Astron. Astrophys. 611 , A66 (2018).

Article   Google Scholar  

Takata, J. et al. A non-thermal pulsed X-ray emission of AR Scorpii. Astrophys. J. 853 , 106 (2018).

Article   ADS   Google Scholar  

Marsh, T. R. et al. A radio-pulsing white dwarf binary star. Nature 537 , 374–377 (2016).

Katz, J. I. AR Sco: a precessing white dwarf synchronar? Astrophys. J. 835 , 150 (2017).

Takata, J., Yang, H. & Cheng, K. S. A model for AR Scorpii: emission from relativistic electrons trapped by closed magnetic field lines of magnetic white dwarfs. Astrophys. J. 851 , 143 (2017).

Potter, S. B. & Buckley, D. A. H. Time series photopolarimetry and modelling of the white dwarf pulsar in AR Scorpii. Mon. Not. R. Astron. Soc. 481 , 2384–2392 (2018).

du Plessis, L. et al. Probing the non-thermal emission geometry of AR Sco via optical phase-resolved polarimetry. Mon. Not. R. Astron. Soc. 510 , 2998–3010 (2022).

Geng, J.-J., Zhang, B. & Huang, Y.-F. A model of white dwarf pulsar AR Scorpii. Astrophys. J. Lett. 831 , L10 (2016).

Barnes, S. A. Ages for illustrative field stars using gyrochronology: viability, limitations, and errors. Astrophys. J. 669 , 1167–1189 (2007).

Hermes, J. J. et al. White dwarf rotation as a function of mass and a dichotomy of mode line widths: Kepler observations of 27 pulsating DA white dwarfs through K2 Campaign 8. Astrophys. J. Suppl. Ser. 232 , 23 (2017).

Córsico, A. H., Althaus, L. G., Miller Bertolami, M. M. & Kepler, S. O. Pulsating white dwarfs: new insights. Astron. Astrophys. Rev. 27 , 7 (2019).

Patterson, J. The DQ Herculis stars. Publ. Astron. Soc. Pac. 106 , 209–238 (1994).

Lyutikov, M. et al. Magnetospheric interaction in white dwarf binaries AR Sco and AE Aqr. Preprint at https://arxiv.org/abs/2004.11474 (2020).

Ghosh, P. & Lamb, F. K. Accretion by rotating magnetic neutron stars. II. Radial and vertical structure of the transition zone in disk accretion. Astrophys. J. 232 , 259–276 (1979).

Pala, A. F. et al. Constraining the evolution of cataclysmic variables via the masses and accretion rates of their underlying white dwarfs. Mon. Not. R. Astron. Soc. 510 , 6110–6132 (2022).

Wynn, G. A. & King, A. R. Diamagnetic accretion in intermediate polars—I. Blob orbits and spin evolution. Mon. Not. R. Astron. Soc. 275 , 9–21 (1995).

Schreiber, M. R., Belloni, D., Gänsicke, B. T., Parsons, S. G. & Zorotovic, M. The origin and evolution of magnetic white dwarfs in close binary stars. Nat. Astron. 5 , 648–654 (2021).

Isern, J., García-Berro, E., Külebi, B. & Lorén-Aguilar, P. A common origin of magnetism from planets to white dwarfs. Astrophys. J. Lett. 836 , L28 (2017).

Ginzburg, S., Fuller, J., Kawka, A. & Caiazzo, I. Slow convection and fast rotation in crystallization-driven white dwarf dynamos. Mon. Not. R. Astron. Soc. 514 , 4111–4119 (2022).

Liebert, J., Ferrario, L., Wickramasinghe, D. T. & Smith, P. S. Enigmas from the Sloan Digital Sky Survey DR7 Kleinman White Dwarf Catalog. Astrophys. J. 804 , 93 (2015).

Parsons, S. G. et al. Magnetic white dwarfs in post-common-envelope binaries. Mon. Not. R. Astron. Soc. 502 , 4305–4327 (2021).

Pala, A. F. et al. A volume-limited sample of cataclysmic variables from Gaia DR2: space density and population properties. Mon. Not. R. Astron. Soc. 494 , 3799–3827 (2020).

Kato, T. & Kojiguchi, N. ZTF J185139.81+171430.3 = ZTF18abnbzvx: the second white dwarf pulsar? Preprint at https://arxiv.org/abs/2107.09913 (2021).

Kato, T., Hambsch, F.-J., Pavlenko, E. P. & Sosnovskij, A. A. Orbital and spin periods of the candidate white dwarf pulsar ASASSN-V J205543.90+240033.5. Preprint at https://arxiv.org/abs/2109.03979 (2021).

Kato, T. Gaia22ayj: outburst from a deeply eclipsing 9.36-min binary? Preprint at https://arxiv.org/abs/2203.13975 (2022).

Dhillon, V. S. et al. ULTRACAM: an ultrafast, triple-beam CCD camera for high-speed astrophysics. Mon. Not. R. Astron. Soc. 378 , 825–840 (2007).

Predehl, P. et al. The eROSITA X-ray telescope on SRG. Astron. Astrophys. 647 , A1 (2021).

Potter, S. B. et al. Polarized QPOs from the INTEGRAL polar IGRJ14536-5522 (=Swift J1453.4-5524). Mon. Not. R. Astron. Soc. 402 , 1161–1170 (2010).

Ricker, G. R. et al. Transiting Exoplanet Survey Satellite (TESS). J. Astron. Telesc. Instrum. Syst. 1 , 014003 (2015).

Tonry, J. L. et al. ATLAS: a high-cadence all-sky survey system. Publ. Astron. Soc. Pac. 130 , 064505 (2018).

Drake, A. J. et al. in New Horizons in Time Domain Astronomy Vol. 285 (eds Griffin, E. et al.) 306–308 (Cambridge Univ. Press, 2012).

Shappee, B. et al. All Sky Automated Survey for SuperNovae (ASAS-SN or ‘Assassin’). In 223rd American Astronomical Society Meeting Abstracts 236.03 (American Astronomical Society, 2014).

Clemens, J. C., Crain, J. A. & Anderson, R. The Goodman spectrograph. Proc. SPIE 5492 , 331–340 (2004).

Vernet, J. et al. X-shooter, the new wide band intermediate resolution spectrograph at the ESO Very Large Telescope. Astron. Astrophys. 536 , A105 (2011).

Caleb, M. et al. Discovery of a radio-emitting neutron star with an ultra-long spin period of 76 s. Nat. Astron. 6 , 828–836 (2022).

Eggleton, P. P. Approximations to the radii of Roche lobes. Astrophys. J. 268 , 368–369 (1983).

Pelisoli, I. et al. Long-term photometric monitoring and spectroscopy of the white dwarf pulsar AR Scorpii. Mon. Not. R. Astron. Soc. 516 , 5052–5066 (2022).

Bailer-Jones, C. A. L., Rybizki, J., Fouesneau, M., Demleitner, M. & Andrae, R. Estimating distances from parallaxes. V. Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3. Astron. J. 161 , 147 (2021).

Eason, E. L. E., Giampapa, M. S., Radick, R. R., Worden, S. P. & Hege, E. K. Spectroscopic and photometric observations of a five-magnitude flare event on UV Ceti. Astron. J 104 , 1161–1173 (1992).

Stepanov, A. V. et al. Multifrequency observations of a flare on UV Ceti. Astron. Astrophys. 299 , 739–750 (1995).

ADS   Google Scholar  

Jurić, M. et al. The Milky Way tomography with SDSS. I. Stellar number density distribution. Astrophys. J. 673 , 864–914 (2008).

Dhillon, V. S. et al. HiPERCAM: a quintuple-beam, high-speed optical imager on the 10.4-m Gran Telescopio Canarias. Mon. Not. R. Astron. Soc. 507 , 350–366 (2021).

Onken, C. A. et al. SkyMapper Southern Survey: second data release (DR2). Publ. Astron. Soc. Aust. 36 , e033 (2019).

Smette, A. et al. Molecfit: a general tool for telluric absorption correction. I. Method and application to ESO instruments. Astron. Astrophys. 576 , A77 (2015).

Kausch, W. et al. Molecfit: a general tool for telluric absorption correction. II. Quantitative evaluation on ESO-VLT/X-Shooter spectra. Astron. Astrophys. 576 , A78 (2015).

Burgh, E. B. et al. Prime Focus Imaging Spectrograph for the Southern African Large Telescope: optical design. Proc. SPIE 4841 , 1463–1471 (2003).

Kobulnicky, H. A. et al. Prime Focus Imaging Spectrograph for the Southern African Large Telescope: operational modes. Proc. SPIE 4841 , 1634–1644 (2003).

Smith, M. P. et al. The Prime Focus Imaging Spectrograph for the Southern African Large Telescope: structural and mechanical design and commissioning. Proc. SPIE 6269 , 62692A (2006).

Buckley, D. A. H., Swart, G. P. & Meiring, J. G. Completion and commissioning of the Southern African Large Telescope. Proc. SPIE 6267 , 62670Z (2006).

Crawford, S. M. et al. PySALT: the SALT science pipeline. Proc. SPIE 7737 , 773725 (2010).

Sunyaev, R. et al. SRG X-ray orbital observatory. Its telescopes and first scientific results. Astron. Astrophys. 656 , A132 (2021).

Brunner, H. et al. The eROSITA Final Equatorial Depth Survey (eFEDS). X-ray catalogue. Astron. Astrophys. 661 , A1 (2022).

Arnaud, K. A. XSPEC: the first ten years. In Astronomical Data Analysis Software and Systems V , Conference Series Vol. 101 (eds Jacoby, G. H. & Barnes, J.) 17 (Astronomical Society of the Pacific, 1996).

CASA Teamet al. CASA, the Common Astronomy Software Applications for radio astronomy. Publ. Astron. Soc. Pac. 134 , 114501 (2022).

Hugo, B. V., Perkins, S., Merry, B., Mauch, T. & Smirnov, O. M. Tricolour: an optimized SumThreshold flagger for MeerKAT. In Astronomical Data Analysis Software and Systems XXX , Conference Series Vol. 532 (eds Ruiz, J. E. et al.) 541 (Astronomical Society of the Pacific, 2022).

Offringa, A. R. et al. WSClean: an implementation of a fast, generic wide-field imager for radio astronomy. Mon. Not. R. Astron. Soc. 444 , 606–619 (2014).

Heywood, I. oxkat: semi-automated imaging of MeerKAT observations. Astrophysics Source Code Library ascl:2009.003 (2020).

Parsons, S. G. et al. The scatter of the M dwarf mass–radius relationship. Mon. Not. R. Astron. Soc. 481 , 1083–1096 (2018).

Littlefield, C. et al. Long-term photometric variations in the candidate white-dwarf pulsar AR Scorpii from K2, CRTS, and ASAS-SN observations. Astrophys. J. Lett. 845 , L7 (2017).

Gänsicke, B. T. et al. Cataclysmic variables from a ROSAT/2MASS selection—I. Four new intermediate polars. Mon. Not. R. Astron. Soc. 361 , 141–154 (2005).

Brown, A. J. et al. Characterizing eclipsing white dwarf M dwarf binaries from multiband eclipse photometry. Mon. Not. R. Astron. Soc. 513 , 3050–3064 (2022).

Kesseli, A. Y., Muirhead, P. S., Mann, A. W. & Mace, G. Magnetic inflation and stellar mass. II. On the radii of single, rapidly rotating, fully convective M-dwarf stars. Astron. J. 155 , 225 (2018).

Hauschildt, P. H., Allard, F. & Baron, E. The NextGen Model Atmosphere grid for 3000 ≤  T eff  ≤ 10,000 K. Astrophys. J. 512 , 377–385 (1999).

Knigge, C., Baraffe, I. & Patterson, J. The evolution of cataclysmic variables as revealed by their donor stars. Astrophys. J. Suppl. Ser. 194 , 28 (2011).

Stiller, R. A. et al. High-time-resolution photometry of AR Scorpii: confirmation of the white dwarf’s spin-down. Astron. J. 156 , 150 (2018).

Gaibor, Y., Garnavich, P. M., Littlefield, C., Potter, S. B. & Buckley, D. A. H. An improved spin-down rate for the proposed white dwarf pulsar AR Scorpii. Mon. Not. R. Astron. Soc. 496 , 4849–4856 (2020).

Bédard, A., Bergeron, P., Brassard, P. & Fontaine, G. On the spectral evolution of hot white dwarf stars. I. A detailed model atmosphere analysis of hot white dwarfs from SDSS DR12. Astrophys. J. 901 , 93 (2020).

Lallement, R. et al. Gaia-2MASS 3D maps of Galactic interstellar dust within 3 kpc. Astron. Astrophys. 625 , A135 (2019).

Tremblay, P. E., Bergeron, P. & Gianninas, A. An improved spectroscopic analysis of DA white dwarfs from the Sloan Digital Sky Survey Data Release 4. Astrophys. J. 730 , 128 (2011).

Camisassa, M. E. et al. Ultra-massive white dwarfs evolution models (Camisassa+, 2019). VizieR Online Data Catalog J/A+A/625/A87 (2019).

Marsh, T. R. in Astrotomography: Indirect Imaging Methods in Observational Astronomy Vol. 573 (eds Boffin, H. M. J. et al.) 1–26 (Springer, 2001).

Garnavich, P. et al. Driving the beat: time-resolved spectra of the white dwarf pulsar AR Scorpii. Astrophys. J. 872 , 67 (2019).

Schmidtobreick, L. et al. Discovery of Hα satellite emission in a low state of the SW Sextantis star BB Doradus. Mon. Not. R. Astron. Soc. 422 , 731–737 (2012).

Maxted, P. F. L., Marsh, T. R., Moran, C., Dhillon, V. S. & Hilditch, R. W. The mass and radius of the M dwarf companion to GD448. Mon. Not. R. Astron. Soc. 300 , 1225–1232 (1998).

Astropy Collaboration et al. Astropy: a community Python package for astronomy. Astron. Astrophys. 558 , A33 (2013).

Price-Whelan, A. M. et al. The Astropy Project: building an open-science project and status of the v2.0 core package. Astron. J. 156 , 123 (2018).

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Acknowledgements

I.P. and T.R.M. acknowledge funding by the UK’s Science and Technology Facilities Council (STFC), grant ST/T000406/1. I.P. also acknowledges funding from a Warwick Astrophysics Prize post-doctoral fellowship, made possible thanks to a generous philanthropic donation. I.P. was additionally supported in part by the National Science Foundation under grant NSF PHY-1748958, and thanks the organizers of the KITP Programme ‘White Dwarfs as Probes of the Evolution of Planets, Stars, the Milky Way and the Expanding Universe’. S.G.P. acknowledges the support of an STFC Ernest Rutherford Fellowship. V.S.D. and ULTRACAM are funded by STFC, grant ST/V000853/1.

This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program.

IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy (AURA) under cooperative agreement with the National Science Foundation (NSF).

This work is based in part on observations obtained at the SOAR telescope, which is a joint project of the Ministério da Ciência, Tecnologia e Inovações do Brasil (MCTI/LNA), the US National Science Foundation’s NOIRLab, the University of North Carolina at Chapel Hill (UNC) and Michigan State University (MSU).

This work is also based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programmes 109.24EM and 109.234F.

The SALT observations were obtained under the SALT Large Science Programme on transients (2021-2-LSP-001; principal investigator D.A.H.B.). Polish participation in SALT is funded by grant MEiN 2021/WK/01. D.A.H.B. and S.B.P. acknowledge research support by the National Research Foundation.

This work has made use of data from the European Space Agency (ESA) mission Gaia ( https://www.cosmos.esa.int/gaia ), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium ). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement.

The MeerKAT telescope is operated by the South African Radio Astronomy Observatory (SARAO), which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. We thank SARAO for the award of the MeerKAT Director’s Discretionary Time.

This work is also based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.

This work is also based on data from eROSITA, the soft X-ray instrument aboard SRG, a joint Russian–German science mission supported by the Russian Space Agency (Roscosmos), in the interests of the Russian Academy of Sciences represented by its Space Research Institute (IKI), and the Deutsches Zentrum für Luft- und Raumfahrt (DLR). The SRG spacecraft was built by Lavochkin Association (NPOL) and its subcontractors, and is operated by NPOL with support from the Max Planck Institute for Extraterrestrial Physics (MPE). The development and construction of the eROSITA X-ray instrument was led by MPE, with contributions from the Dr. Karl Remeis Observatory Bamberg & ECAP (FAU Erlangen-Nürnberg), the University of Hamburg Observatory, the Leibniz Institute for Astrophysics Potsdam (AIP) and the Institute for Astronomy and Astrophysics of the University of Tübingen, with the support of DLR and the Max Planck Society. The Argelander Institute for Astronomy of the University of Bonn and the Ludwig-Maximilians-Universität Munich also participated in the science preparation for eROSITA. The eROSITA data shown here were processed using the eSASS/NRTA software system developed by the German eROSITA consortium.

Support of the Deutsche Forschungsgemeinschaft (DFG) under grant number 536/37-1 is gratefully acknowledged.

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Department of Physics, University of Warwick, Coventry, UK

Ingrid Pelisoli, T. R. Marsh & James Munday

South African Astronomical Observatory, Cape Town, South Africa

David A. H. Buckley, Stephen. B. Potter & Jaco Brink

Department of Astronomy, University of Cape Town, Rondebosch, South Africa

David A. H. Buckley, Jaco Brink & P. A. Woudt

Department of Physics, University of the Free State, Bloemfontein, South Africa

David A. H. Buckley

Astrophysics, Department of Physics, University of Oxford, Oxford, UK

Department of Physics and Electronics, Rhodes University, Makhanda, South Africa

South African Radio Astronomy Observatory, Cape Town, South Africa

Department of Physics, University of Johannesburg, Auckland Park, South Africa

Stephen. B. Potter

Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany

Axel Schwope & Annie Standke

Institute for Physics and Astronomy, University of Potsdam, Potsdam, Germany

Annie Standke

Department of Physics and Astronomy, University of Sheffield, Sheffield, UK

S. G. Parsons, A. J. Brown, V. S. Dhillon, M. J. Dyer, P. Kerry, S. P. Littlefair, D. I. Sahman & J. F. Wild

School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv, Israel

M. J. Green

Instituto de Física, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

S. O. Kepler & A. D. Romero

Isaac Newton Group of Telescopes, Santa Cruz de La Palma, Spain

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Contributions

All authors contributed to the work presented in this paper. I.P. wrote the manuscript and led the follow-up and analysis of the system, with substantial input from T.R.M. D.A.H.B. carried out follow-up observations at SAAO and contributed to analysis of the optical data. I.H. carried out reduction and analysis of the radio data. S.B.P. carried out follow-up observations at SAAO and the analysis and modelling of polarimetric data. A. Schwope and A. Standke obtained and analysed the X-ray data. P.A.W. obtained the radio data. S.G.P. and M.J.G. contributed to initial identification and analysis of the system. S.O.K., J.M. and A.D.R. contributed to observational follow-up. E.B., A.J.B., V.S.D., M.J.D., P.K., S.P.L., D.I.S. and J.F.W. contributed to the maintenance of operations of ULTRACAM.

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Correspondence to Ingrid Pelisoli .

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Extended data

Extended data fig. 1 optical spectrum of j1912-4410..

The black line shows the SOAR spectrum obtained for J1912-4410, which confirmed its spectral characteristics to be similar to AR Sco. The grey line shows X-Shooter spectra from the UVB and VIS arms obtained around the same orbital phase as the SOAR spectrum (0.85). The flux calibration of the SOAR spectrum is poor towards the blue due to reduced sensitivity.

Extended Data Fig. 2 Constraints from Roche geometry.

In panel (a) the star marks measurements from the NaII line (by our definition the centre of mass of the M dwarf). The cross, diamond, and circle mark respectively H α , H β , and H γ , which were fitted as \(V=\gamma -{V}_{X}\cos (2\pi \varphi )+{V}_{Y}\sin (2\pi \varphi )\) , where φ is the orbital phase and γ , the systemic velocity, was kept fixed to the previously determined value. The one-sigma uncertainties are comparable to the symbol size. H β , and H γ give consistent measurements, whereas H α seems to trail the leading face of the M dwarf. The red dashed line is the Roche lobe of the M dwarf for q  = 0.1. The black cross and blue triangle mark the centre of mass of the system and of the white dwarf, respectively. The black line in panel (b) shows the expected difference between the irradiated face and centre-of mass radial velocity semi-amplitudes as a function of q , assuming the M dwarf fills its Roche lobe. The right-hand y-axis shows the required inclination to explain the detected K difference. The observed value of K difference sets a minimum for q , which would happen if the system was seen at 90 ∘ inclination, as indicated by the red dashed line. The area shaded in grey corresponds to M 1 values consistent with a white dwarf for a Roche lobe-filling companion, and implies the minimum q value of 0.3. This minimum q corresponds to a maximum inclination of 37 ∘ (blue dashed lines).

Extended Data Fig. 3 Constraints from the binary mass function.

The colour map shows the required inclination to explain the observed K 2 for given values of M 1 and M 2 shown in the x- and y-axis. The red line marks the maximum inclination of 37 ∘ , derived from Roche geometry, and the blue shaded area indicates the M 2 mass derived from a mass–radius relationship. Given the high systematic uncertainty on M 2 , we adopt less strict constraints of M 1 = 1.2 ± 0.2 M ⊙ and M 2 = 0.25 ± 0.05 M ⊙ .

Extended Data Fig. 4 Pulse shape for different orbital phases and nights.

The thick red line shows all the X-ray data averaged to 20 phase bins (with an average of 93 measurements per bin) and folded on the spin ephemeris. The uncertainty on the mean is shown for spin phase 0 to 1. The thin lines and symbols show ULTRACAM g s data averaged to 20 phase bins (with an average of 16 measurements per bin) and folded on the same ephemeris, but considering data only within the orbital phase ranges shown on the right of the plot. Uncertainties on the mean are shown for spin phase 1 to 2. The green dashed line shows data taken on 2022 June 07, the black symbols are data taken on 2022 September 17 (simultaneously with the X-ray data) with one-sigma uncertainties, and the solid blue line shows data for 2022 September 23. All data were normalised to the strongest peak to facilitate comparison. As also seen in Fig. 2 , the peak of the X-ray pulses does not align with the bulk of optical pulses. However, it does align with the optical peaks observed on 2022 September 17. This difference cannot be attributed to uncertainty in the ephemeris, given the agreement between data taken on nights before and after the X-ray observations. Additional simultaneous data is needed to determine the cause of misalignment, which could possibly be due to sporadic changes on pulse profile.

Extended Data Fig. 5 Flux and colour of the possible flare.

Panel (a) shows the flux in the u s (blue triangles), g s (green circles), and r s (red crosses) bands, with respective one-sigma uncertainties for each measurement, in the region of the feature that we identify as a flare (marked by the shaded grey area). Panels (b) and (c) show the u s - g s and g s - r s colours, again with one-sigma uncertainties. Unlike typical M dwarf flares, there is no evidence of flux increase towards the blue.

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Pelisoli, I., Marsh, T.R., Buckley, D.A.H. et al. A 5.3-min-period pulsing white dwarf in a binary detected from radio to X-rays. Nat Astron 7 , 931–942 (2023). https://doi.org/10.1038/s41550-023-01995-x

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White Dwarf Stars

computer science, laboratory astrophysics, mathematics, physics, stellar astronomy

Our Research

In our stream, we use white dwarfs and other stars to study many topics in astronomy and physics. We also conduct laboratory astrophysics experiments on the Z machine at Sandia National Labs in Albuquerque, NM, to study the absorption and emission of light in dense stellar plasmas. Finally, we use the stellar simulation code MESA to model the evolution and interior structure of white dwarfs and other stars.

White Dwarf Stars Research Targets

• ages of different stellar populations
• pulsations of stars
• physics of convection
• physics of crystallization in stellar interiors

Our Strategy

In our laboratory, researchers perform data reduction, programming, and plotting using Python programming language plus Astropy and assorted modules.  At the highest level, students develop the ability to organize and follow through on a research project, and they become more confident in presenting their work. They also become more proficient in writing (and debugging) software that they themselves create.

White Dwarfs researchers focus on:

• how to reduce astronomical image data
• performing aperture photometry
• time series data analysis
• using state-of-the-art stellar evolution code MESA

The main goals of our stream are to further our knowledge of the Universe through the study of stars and to allow students to gain the knowledge and experience that will help them succeed in their future careers. 

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• Sanghi, A., Vanderbosch, Z. P., & Montgomery, M. H. Identifying Periodic Variable Stars and Eclipsing Binary Systems with Long-term Las Cumbres Observatory Photometric Monitoring of ZTF J0139+5245”, 2021 , AJ , 162 (4), 133.

Guidry, J. A., Vanderbosch, Z. P., Hermes, J. J., Barlow, B. N., Lopez, I. D., Boudreaux, T. M., Corcoran, K. A., Bell, K. J., Montgomery, M. H., Heintz, T. M., Castanheira, B. G., Reding, J. S., Dunlap, B. H., Winget, D. E., Winget, K. I., & Kuehne, J. W. I Spy Transits and Pulsations: Empirical Variability in White Dwarfs Using Gaia and the Zwicky Transient Facility . 2021 , ApJ , 912 (2), 125.

Montgomery, M. H., Winget, D. E., Allen, A., Falcon, R. E., Gomez, J., Ellis, J., Havanur, V., Luecke, K., Melin, K., Miller, G., & Rendon, C., 2010, In New Horizons in Astronomy: Frank N. Bash Symposium 2009, ed. L. M. Stanford, J. D. Green, L. Hao, & Y. Mao. Exploring the Universe with White Dwarf Stars: The First Year of the Freshman Research Initiative” . Volume 432 of Astronomical Society of the Pacific Conference Series, 225.

Astronomy & Astrophysics 101: White Dwarf

What Is a White Dwarf?

A white dwarf is the stellar core left behind after a dying star has exhausted its nuclear fuel and cast off its outer layers to form a planetary nebula.

Evolution and Characteristics of White Dwarfs

The ultimate fate of a star depends on its initial mass. There are several possible ways in which certain stars (with initial masses between around 80% to 10 times that of the Sun) might eventually become white dwarfs.

The vast majority of white dwarfs are formed after a dying star has expelled its outer layers to form a planetary nebula , leaving behind an approximately Earth-sized inner core that is the white dwarf. Other white dwarfs in binary systems may explode as novae but then not go on to form a neutron star or a black hole . More massive stars have a different fate and explode as supernovae .

White dwarfs no longer support nuclear fusion reactions that generate energy, but they are still extremely hot. They cool over time, and it is predicted that they would ultimately form ‘black dwarfs’, although the Universe is likely not old enough for any black dwarfs to exist yet.

The luminosity of white dwarfs can therefore be used by astronomers to measure how long ago star formation began in a particular region. By providing important ‘fossil’ records of the stars that they formed from, white dwarfs are an important cosmological tool.

Observational Breakthroughs in White Dwarf Studies

In 2006 Hubble was the first telescope to directly observe white dwarfs in globular star clusters , which astronomers reported as the dimmest stars ever seen in a globular star cluster. Hubble’s Advanced Camera for Surveys completed a census of two distinct stellar populations in one cluster, known as NGC 6397, and surveyed the faintest dwarf stars.

Hubble’s Discoveries in White Dwarf Research

In 2013 Hubble found signs of Earth-like planets in the atmospheres of a pair of white dwarf stars roughly 150 light-years away and only 625 million years old. Hubble’s spectroscopic observations identified silicon in the atmospheres of the two white dwarfs, a major ingredient of the rocky material that forms Earth and other terrestrial planets in the Solar System. Silicon may have come from asteroids that were shredded by the white dwarfs’ gravity when they veered too close to the stars. The rocky debris likely formed a ring around the dead stars, which then funneled the material inwards.

Related Articles

Astronomy & astrophysics 101: star, astronomy & astrophysics 101: red giant, hubble find surprises astronomers: white dwarfs can still undergo stable thermonuclear activity, bizarre, metallic star spotted hurtling out of the milky way at 2 million miles an hour, hubble solves mystery of monster star’s dimming – red hypergiant is as bright as 300,000 suns, hubble views stars’ clockwork motion in nearby galaxy, hubble reveals link between stars’ ages and their orbits, nasa data reveals significant changes in exoplanet’s atmosphere, hubble observes rare blue stars in andromeda’s core.

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White dwarfs: Facts about the dense stellar remnants

White dwarfs are among the densest objects in space.

White dwarf formation

White dwarf characteristics, the fate of a white dwarf, additional resources, bibliography.

White dwarfs are what is left when stars like our sun have exhausted all of their fuel. They are dense, dim, stellar corpses — the last observable stage of evolution for low- and medium-mass stars.  

Whilst most massive stars will eventually go supernova, a low or medium mass star with a mass less than about 8 times the mass of the sun will eventually become a white dwarf, according to NASA . Approximately 97% of the stars in the Milky Way will eventually become white dwarfs, according to researchers .

Compared to our sun , a white dwarf has a similar carbon and oxygen mass though it is much smaller in size — similar to Earth , according to New Mexico State University (NMSU). 

White dwarf temperatures can exceed 100,000 Kelvin according to NASA (that's about 179,500 degrees Fahrenheit). Despite these sweltering temperatures, white dwarfs have a low luminosity as they're so small in size according to NMSU.

Related: Red dwarfs: The most common and longest-lived stars

Main-sequence stars , including the sun, form from clouds of dust and gas drawn together by gravity. How the stars evolve through their lifetime depends on their mass. The most massive stars, with eight times the mass of the sun or more, will never become white dwarfs. Instead, at the end of their lives, white dwarfs will explode in a violent supernova , leaving behind a neutron star  or black hole .

According to NASA, a teaspoon of white dwarf matter would weigh 5.5 tons on Earth — about the same as an elephant!  

Smaller stars, however, will take a slightly more sedate path. Low- to medium-mass stars, such as the sun , will eventually swell up into red giants . After that, the stars shed their outer layers into a ring known as a planetary nebula  (early observers thought the nebulas resembled planets such as Neptune and Uranus ). The core that is left behind will be a white dwarf, a husk of a star in which no hydrogen fusion occurs.

Smaller stars, such as red dwarfs, don't make it to the red giant state. They simply burn through all of their hydrogen, ending the process as a dim white dwarf. However, red dwarfs take trillions of years to consume their fuel, far longer than the 13.8-billion-year-old age of the universe, so no red dwarfs have yet become white dwarfs.

When a star runs out of fuel, it no longer experiences an outward push from the process of fusion and it collapses inward on itself. White dwarfs contain approximately the mass of the sun but have roughly the radius of Earth, according to Cosmos , the astronomy encyclopedia from Swinburne University in Australia. This makes them among the densest objects in space, beaten out only by neutron stars and black holes. According to NASA, the gravity on the surface of a white dwarf is 350,000 times that of gravity on Earth. That means a 150-pound (68-kilogram) person on Earth would weigh 50 million pounds (22.7 million kg) on the surface of a white dwarf.

White dwarfs reach this incredible density because they are collapsed so tightly that their electrons are smashed together, forming what is called "degenerate matter." The former stars will keep collapsing until the electrons themselves provide enough of an outward-pressing force to halt the crunch. The more mass, the greater the pull inward, so a more massive white dwarf has a smaller radius than its less massive counterpart. Those conditions mean that, after shedding much of its mass during the red giant phase, no white dwarf can exceed 1.4 times the mass of the sun .

When a star swells up to become a red giant, it engulfs its closest planets. But some can still survive. NASA’s Spitzer spacecraft  revealed that at least 1 to 3 percent of white dwarf stars have contaminated atmospheres that suggest rocky material has fallen into them.

– How many stars are in the universe?

– What is the biggest star ever observed?

– White holes: What we know about black holes' neglected twins  

"In the quest for Earth-like planets, we have now identified numerous systems which are excellent candidates to harbor them," Jay Farihi, a white dwarf researcher at the University of Leicester in England, told Space.com . "Where they persist as white dwarfs, any terrestrial planets will not be habitable, but may have been sites where life developed during a previous epoch."

In one exciting case, researchers have observed the rocky material as it falls into the white dwarf.

"It's exciting and unexpected that we can see this kind of dramatic change on human timescales," Boris Gänsicke, an astronomer at the University of Warwick in England, told Space.com .

Many white dwarfs fade away into relative obscurity, eventually radiating away all of their energy and becoming so-called black dwarfs , but those that share a system with companion stars may suffer a different fate. 

If the white dwarf is part of a binary system, it may be able to pull material from its companion onto its surface. Increasing the white dwarf's mass can have some interesting results.

One possibility is that the added mass could cause it to collapse into a much denser neutron star.

A far more explosive result is the Type 1a supernova . As the white dwarf pulls material from a companion star, the temperature increases, eventually triggering a runaway reaction that detonates in a violent supernova that destroys the white dwarf. This process is known as a "single-degenerate model" of a Type 1a supernova. 

Related: Know Your Novas: Star Explosions Explained (Infographic)  

In 2012, researchers were able to closely observe the complex shells of gas surrounding one Type 1a supernova in fine detail.

"We really saw, for the first time, detailed evidence of the progenitor for a Type 1a supernova," Benjamin Dilday, the study's lead author and an astronomer at Las Cumbres Observatory Global Telescope Network in California told SPACE.com .

If the companion is another white dwarf instead of an active star, the two stellar corpses merge together  to kick off the fireworks. This process is known as a "double-degenerate model" of a Type 1a supernova.

At other times, the white dwarf may pull just enough material from its companion to briefly ignite in a nova, a far smaller explosion. Because the white dwarf remains intact, it can repeat the process several times when it reaches that critical point, breathing life back into the dying star over and over again.

"These are the brightest and most frequent stellar eruptions in the galaxy, and they're often visible to the naked eye," Przemek Mróz, an astronomer at Poland’s Warsaw University, told Space.com in a previous article .

You can learn more about white dwarfs with ESA and explore different types of stars with NASA . Discover the evolution of binary star systems with this free educational material from Lumen Learning . Explore the physics of the universe with white dwarfs in this informative material from The University of Texas at Austin .

• Dilday, B., et al. " PTF 11kx: A type Ia supernova with a symbiotic nova progenitor. " Science 337.6097 (2012): 942-945. 
• Fontaine, G., P. Brassard, and P. Bergeron. " The Potential of White Dwarf Cosmochronology1. " Publications of the Astronomical Society of the Pacific 113.782 (2001): 409. 
• Horowitz, C. J. " Nuclear and dark matter heating in massive white dwarf stars. " Physical Review D 102.8 (2020): 083031. 
• Bédard, A., et al. " On the spectral evolution of hot white dwarf stars. I. A detailed model atmosphere analysis of hot white dwarfs from SDSS DR12. " The Astrophysical Journal 901.2 (2020): 93. 
• ESA " Shedding light on white dwarfs — the future of stars like our sun. " 2019 

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white dwarf star , any of a class of faint stars representing the endpoint of the evolution of intermediate- and low-mass stars. White dwarf stars, so called because of the white colour of the first few that were discovered, are characterized by a low luminosity , a mass on the order of that of the Sun , and a radius comparable to that of Earth . Because of their large mass and small dimensions, such stars are dense and compact objects with average densities approaching 1,000,000 times that of water.

Unlike most other stars that are supported against their own gravitation by normal gas pressure, white dwarf stars are supported by the degeneracy pressure of the electron gas in their interior. Degeneracy pressure is the increased resistance exerted by electrons composing the gas, as a result of stellar contraction ( see degenerate gas ). The application of the so-called Fermi-Dirac statistics and of special relativity to the study of the equilibrium structure of white dwarf stars leads to the existence of a mass-radius relationship through which a unique radius is assigned to a white dwarf of a given mass; the larger the mass, the smaller the radius. Furthermore, the existence of a limiting mass is predicted, above which no stable white dwarf star can exist. This limiting mass, known as the Chandrasekhar limit , is on the order of 1.4 solar masses. Both predictions are in excellent agreement with observations of white dwarf stars.

The central region of a typical white dwarf star is composed of a mixture of carbon and oxygen . Surrounding this core is a thin envelope of helium and, in most cases, an even thinner layer of hydrogen . A very few white dwarf stars are surrounded by a thin carbon envelope. Only the outermost stellar layers are accessible to astronomical observations.

White dwarfs evolve from stars with an initial mass of up to three or four solar masses or even possibly higher. After quiescent phases of hydrogen and helium burning in its core—separated by a first red-giant phase—the star becomes a red giant for a second time. Near the end of this second red-giant phase, the star loses its extended envelope in a catastrophic event, leaving behind a dense, hot, and luminous core surrounded by a glowing spherical shell. This is the planetary-nebula phase . During the entire course of its evolution, which typically takes several billion years, the star will lose a major fraction of its original mass through stellar winds in the giant phases and through its ejected envelope. The hot planetary-nebula nucleus left behind has a mass of 0.5–1.0 solar mass and will eventually cool down to become a white dwarf.

White dwarfs have exhausted all their nuclear fuel and so have no residual nuclear energy sources. Their compact structure also prevents further gravitational contraction. The energy radiated away into the interstellar medium is thus provided by the residual thermal energy of the nondegenerate ions composing its core. That energy slowly diffuses outward through the insulating stellar envelope, and the white dwarf slowly cools down. Following the complete exhaustion of this reservoir of thermal energy, a process that takes several additional billion years, the white dwarf stops radiating and has by then reached the final stage of its evolution and becomes a cold and inert stellar remnant. Such an object is sometimes called a black dwarf.

White dwarf stars are occasionally found in binary systems, as is the case for the white dwarf companion to the brightest star in the night sky, Sirius . White dwarf stars also play an essential role in Type Ia supernovae and in the outbursts of novae and of other cataclysmic variable stars .

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Shedding light on white dwarfs – the future of stars like our sun.

17 May 2019

White dwarfs are the remnants left behind when medium-sized stars like our Sun reach the end of their lives. These stellar relics are extremely dense, with masses comparable to the Sun's confined to volumes comparable to that of Earth; just one cubic centimetre can weigh an incredible 1000 kilograms. Finding out more about white dwarfs gives us a peek into the future, showing us what the Sun will be like in five billion years' time, once it has exhausted the fuel powering nuclear fusion reactions at its core.

White dwarfs were discovered in 1910, when astronomers observed some mysterious objects that didn't fit with the then accepted model of stellar evolution. But it took almost 50 years to find as many as one hundred of them.

Until recently, just 30 000 white dwarfs had been discovered – a tiny number compared to the few hundred billion stars that are believed to exist within the Milky Way alone. And because they radiate only a small amount of lingering thermal energy as they slowly cool down, they are very faint and so it has been difficult to uncover much about them.

Enter the Gaia era

Now, thanks to the game-changing second batch of data from Gaia, 486 641 white dwarf candidates have been detected, with 260 000 of these being high-confidence candidates, as reported in a catalogue compiled by Nicola Pietro Gentile Fusillo and collaborators. Discovering more of these mysterious objects enables us to gain better knowledge of their properties, improving our understanding of how they fit into the overall picture of stellar evolution.

" Thanks to Gaia's incredible ability to pinpoint the 3D position of huge numbers of stars, not only are we finding many more white dwarfs than we previously knew to exist, but our knowledge of their distances is hugely improving, " explains Gaia scientist Stefan Jordan of Astronomisches Rechen-Institut, Zentrum für Astronomie in Heidelberg, Germany. " This allows us to decipher other properties of these stars better than we ever could in the past. "

The huge number of newly-discovered white dwarfs also means that many new classes and configurations have been revealed that didn't appear in the original 30 000. These include the first triple white dwarf system described in a paper by Marti Perpinyà-Vallès and colleagues : the triplet features three white dwarfs of the same age, which is strange if we consider that these objects are the relics of dead stars and therefore should all have formed at different times.

The Gaia catalogue includes lots of particularly cool white dwarfs, usually difficult to spot because they are so dim, as reported in studies led by Gustavo Ourique , Rodrigo González Peinado and Simon Blouin .

One of the most interesting discoveries to come out of this data release, made by Pier-Emmanuel Tremblay and collaborators , was the revelation that the cores of white dwarfs turn solid as they cool down , effectively forming extremely giant cosmic diamonds that are a million times denser than the Earth-based diamonds we are used to. This phenomenon was predicted 50 years ago by Hugh van Horn but little was understood about the process until Gaia data indicated white dwarfs release latent heat as they transform into crystals, slowing down the cooling process temporarily. The results suggest that after the Sun becomes a white dwarf in five billion years, it will take another five billion years for its core to turn solid.

White dwarfs inside out

The majority of white dwarfs are made up of mostly one element – typically hydrogen or helium, and in rare cases, carbon. But some have thick atmospheres, which can be polluted with heavier elements such as calcium, magnesium and iron. The new data contains information on previously-unknown polluted white dwarfs, the first of them announced in a research note by Carl Melis and collaborators ; these objects are interesting because the polluting elements are thought to come from surrounding dusty disks or even unseen exoplanets or asteroids that have merged with the white dwarfs' outer layers.

Dusty disks can also lead to variability in the amount of infrared radiation that we receive from these stellar relics. One study led by Siyi Xu looked at Gaia observations of two white dwarfs that show such variability, suggesting that exoplanets could be disrupting the dusty disk.

Many new extremely low-mass white dwarfs have also been discovered in the new catalogue, as described in a paper by Ingrid Pelisoli and colleagues . The origin of these low-mass white dwarfs remains a mystery, and they don't fit with current models of stellar evolution. Finding more of them could help us better understand stars overall.

Furthermore, Gaia is enabling astronomers to study pulsating white dwarfs in greater detail. This special variety of white dwarf allows astronomers to carry out 'asteroseismology' research and study their interiors, just like seismology on Earth is used to understand the interior of our planet. Robert A. Stiller and collaborators used data from Gaia's second release to investigate the interaction between a pulsating white dwarf and its red-dwarf companion. Another study, led by Mukremin Kilic , looked for pulsations in white dwarf companions to millisecond pulsars, which are rapidly rotating, highly magnetised neutron stars – the endpoint of massive stars – and found pulsating emission from one such pair.

Near and far – white dwarfs across the Galaxy

The closest known white dwarf to Earth is Sirius B, companion of the brightest star in the night sky, Sirius A, only eight light years away. The Gaia data contained new information about Sirius A's dim companion, which were used by Simon R. G. Joyce and collaborators to improve our knowledge of the fundamental relationship between the mass and radius of white dwarfs.

White dwarfs are also advancing our understanding of the Milky Way as a whole. Because they cool at specific rates, they are good indicators of the age of different parts of the Galaxy. Using information from Gaia on more than 150 000 of the coolest and faintest white dwarfs, Mukremin Kilic and colleagues estimated the halo of stars surrounding the Milky Way to be about 11 billion years old, helping to pin down the evolutionary history of our galaxy.

Gaia is also providing new insight into the progenitors of white dwarfs. In particular, two papers led respectively by Jeffrey D. Cummings and Kareem El-Badry used the data to investigate the relationship between the mass of a star and the mass of the white dwarf that it eventually morphs into. It is expected that future releases of Gaia data will clarify this further, helping us predict the Sun's future in greater detail.

In a different study, Ken Shen and colleagues exploited Gaia's information not only on the position and distance of stars but also on their velocities across the Milky Way to find three white dwarfs that are zipping through our Galaxy at very high speeds. One possible interpretation sees these hyper-velocity white dwarfs as the survivors of a particular type of thermonuclear explosion, known as a type-Ia supernova. These explosions happen when a white dwarf pulls matter from a stellar companion in a binary system; in this particular case, the astronomers believe that the explosion happened in a system of two white dwarfs, causing one of the two stellar remnants to disappear and throwing the other away at speeds over 1000 kilometres per second. Gaia data on the motion of one of these speedy white dwarfs even hints at the existence of a supernova remnant.

More excitement awaits white dwarf researchers. Based on Gaia data, Peter McGill and collaborators predicted that on 11 November 2019 a nearby white dwarf will pass in front of a more distant star. The white dwarf's gravity will deflect and magnify the background star's light, acting as a gravitational lens: this unique opportunity will allow astronomers to determine the white dwarf's mass. Until and after then, scientists will keep working with existing data from Gaia and other surveys to slowly but surely unveil the many mysteries of white dwarfs.

" Since Gaia was designed with 'galactic archaeology' as its main priority, we always expected that the mission would make ground-breaking discoveries in a diverse range of areas in astronomy, " concludes ESA's Gaia deputy project scientist, Jos de Bruijne. " It is extremely rewarding to witness such a large contribution to white dwarf science from this latest data release. "

A huge amount remains to be discovered about white dwarfs, but with Gaia, we are deciphering these fascinating objects one step at a time.

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Https://sci.esa.int/s/welel3w, images and videos.

The hyper-velocity white dwarf D6-2

Gaia white dwarf discoveries, the motions of 230 000 white dwarfs, white dwarf cooling sequence and crystallisation, artist's impression of crystallisation in white dwarf, artist's impression of the sizes of sirius b and the earth, an artist's impression of sirius a and b.

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• News Release: June 23, 2014 at 4:00 pm EDT

Remarkable White Dwarf Star Possibly Coldest, Dimmest Ever Detected

A team of astronomers has identified possibly the coldest, faintest white dwarf star ever detected. This ancient stellar remnant is so cool that its carbon has crystallized, forming — in effect — an Earth-size diamond in space.

“It’s a really remarkable object,” said David Kaplan, a professor at the University of Wisconsin-Milwaukee. “These things should be out there, but because they are so dim they are very hard to find.”

Kaplan and his colleagues found this stellar gem using the National Radio Astronomy Observatory’s (NRAO) Green Bank Telescope (GBT) and Very Long Baseline Array (VLBA), as well as other observatories.

White dwarfs are the extremely dense end-states of stars like our Sun that have collapsed to form an object approximately the size of the Earth. Composed mostly of carbon and oxygen, white dwarfs slowly cool and fade over billions of years. The object in this new study is likely the same age as the Milky Way, approximately 11 billion years old.

Pulsars are rapidly spinning neutron stars, the superdense remains of massive stars that have exploded as supernovas. As neutron stars spin, lighthouse-like beams of radio waves, streaming from the poles of its powerful magnetic field, sweep through space. When one of these beams sweeps across the Earth, radio telescopes can capture the pulse of radio waves.

The pulsar companion to this white dwarf, dubbed PSR J2222-0137, was the first object in this system to be detected. It was found using the GBT by Jason Boyles, then a graduate student at West Virginia University in Morgantown.

These first observations revealed that the pulsar was spinning more than 30 times each second and was gravitationally bound to a companion star, which was initially identified as either another neutron star or, more likely, an uncommonly cool white dwarf. The two were calculated to orbit each other once every 2.45 days.

The pulsar was then observed over a two-year period with the VLBA by Adam Deller, an astronomer at the Netherlands Institute for Radio Astronomy (ASTRON). These observations pinpointed its location and distance from the Earth — approximately 900 light-years away in the direction of the constellation Aquarius. This information was critical in refining the model used to time the arrival of the pulses at the Earth with the GBT.

By applying Einstein’s theory of relativity, the researchers studied how the gravity of the companion warped space, causing delays in the radio signal as the pulsar passed behind it. These delayed travel times helped the researchers determine the orientation of their orbit and the individual masses of the two stars. The pulsar has a mass 1.2 times that of the Sun and the companion a mass 1.05 times that of the Sun.

These data strongly indicated that the pulsar companion could not have been a second neutron star; the orbits were too orderly for a second supernova to have taken place.

Knowing its location with such high precision and how bright a white dwarf should appear at that distance, the astronomers believed they should have been able to observe it in optical and infrared light.

Remarkably, neither the Southern Astrophysical Research (SOAR) telescope in Chile nor the 10-meter Keck telescope in Hawaii was able to detect it.

“Our final image should show us a companion 100 times fainter than any other white dwarf orbiting a neutron star and about 10 times fainter than any known white dwarf, but we don’t see a thing,” said Bart Dunlap, a graduate student at the University of North Carolina at Chapel Hill and one of the team members. “If there’s a white dwarf there, and there almost certainly is, it must be extremely cold.”

The researchers calculated that the white dwarf would be no more than a comparatively cool 3,000 degrees Kelvin (2,700 degrees Celsius). Our Sun at its center is about 5,000 times hotter.

Astronomers believe that such a cool, collapsed star would be largely crystallized carbon, not unlike a diamond. Other such stars have been identified and they are theoretically not that rare, but with a low intrinsic brightness, they can be deucedly difficult to detect. Its fortuitous location in a binary system with a neutron star enabled the team to identify this one.

A paper describing these results is published in the Astrophysical Journal .

The National Radio Astronomy Observatory is a facility of the National Science Foundation , operated under cooperative agreement by Associated Universities, Inc .

Charles Blue, Public Information Officer National Radio Astronomy Observatory +1 434-296-0314; [email protected]

Dr. Katy Garmany, Deputy Press Officer National Optical Astronomy Observatory +1 520-318-8526; [email protected]

David Kaplan Asst. Professor Dept. of Physics, UW-Milwaukee +1-414-229-4971; [email protected]

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A team of astronomers has found a new tool to discover pulsars. Pulsars are rapidly rotating neutron stars that blast out pulses of radiation at regular intervals ranging from seconds to milliseconds.

An unusual group of stars in the Orion constellation have revealed their secrets. FU Orionis, a double star system, first caught astronomers’ attention in 1936 when the central star suddenly became 1,000 times brighter than usual. This behavior, expected from dying stars, had never been seen in a young star like FU Orionis. The strange phenomenon inspired a new classification of stars sharing the same name (FUor stars). FUor stars flare suddenly, erupting in brightness, before dimming again many years later. It is now understood that this brightening is due to the stars taking in energy from their surroundings via gravitational accretion, the main force that shapes stars and planets. However, how and why this happens remained a mystery—until now, thanks to astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA).

Astronomers have discovered the secrets of a starburst galaxy producing new stars at a rate much faster than our…

New theory explains why white dwarf stars can cheat death

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In a paper published today in Nature , scholars from the Institute for Advanced Study; the University of Victoria, Canada; and the University of Warwick, U.K., have proposed a new theory that explains why a puzzling population of white dwarf stars stopped cooling for ten billion years. 

Open any astronomy textbook to the section on white dwarf stars and you’ll likely learn that they are "dead stars" that continuously cool down over time. The cooling occurs because the white dwarfs have depleted their nuclear heat source. In the classic picture, this causes the dense plasma in a white dwarf’s interior to freeze, leading the star to solidify from the inside out. 

However, an analysis of data from the European Space Agency’s Gaia  satellite, published in 2019 by Sihao Cheng , Martin A. and Helen Chooljian Member in the Institute’s School of Natural Sciences , contradicted this standard picture. It showed that some white dwarfs in fact remain hot for many billions of years (a large portion of the age of the Universe). This finding had confounded theorists, but today’s new paper might provide a compelling explanation.

"In order for these white dwarfs to cease cooling down, they must somehow produce additional energy," says Cheng, who also contributed to the Nature paper. "Although we were initially uncertain about what this process might be, we now have a clearer understanding of how it occurs."

This understanding was developed through a collaboration between Cheng, Antoine Bédard of the University of Warwick, and Simon Blouin of the University of Victoria. 

They propose that in some white dwarfs, the dense plasma in the interior does not simply freeze from the inside out. Instead, the solid crystals that are formed upon freezing are less dense than the liquid, and therefore begin to float towards the surface. As the crystals float upwards, they displace the heavier liquid downward. The transport of denser material toward the center of the star releases gravitational energy, and this energy is enough to interrupt the star’s cooling process for billions of years.

"One fascinating aspect of this discovery is that the physics involved is similar to something we observe in daily life: the frozen crystals within the white dwarf star float instead of sink. We might compare their behavior to ice cubes floating in water," says Cheng. 

Why this happens in some white dwarfs and not others is uncertain, but the authors think it is likely due to the composition of the star. 

"Some white dwarf stars are formed by the merger of two different stars. When these stars collide to form the white dwarf, it changes the composition of the star in a way that can allow the formation of floating crystals," says Blouin.

White dwarfs are routinely used as age indicators: the cooler a white dwarf is, the older it is assumed to be. However, due to the extra delay in cooling found in some white dwarfs, some stars of a given temperature may be billions of years older than previously thought. Better understanding the ages and other aspects of white dwarf stars will help scientists reconstruct the formation of our galaxy.

"Our work will necessitate updates to astronomy textbooks," adds Cheng. "We hope that it will also prompt astronomers to reassess the methods employed to calculate the age of stellar populations."

The research is supported by the National Sciences and Engineering Research Council of Canada (NSERC), the Banting Postdoctoral Fellowship program, the European Research Council, the Canadian Institute for Theoretical Astrophysics (CITA), and the Institute for Advanced Study's Fund for Natural Sciences.

This news is adapted from a press release issued by the University of Victoria . Press releases were also produced by CITA and by the University of Warwick .

About the Institute

The Institute for Advanced Study has served the world as one of the leading independent centers for theoretical research and intellectual inquiry since its establishment in 1930, advancing the frontiers of knowledge across the sciences and humanities. From the work of founding IAS faculty such as Albert Einstein and John von Neumann to that of the foremost thinkers of the present, the IAS is dedicated to enabling curiosity-driven exploration and fundamental discovery.

Each year, the Institute welcomes more than 200 of the world’s most promising post-doctoral researchers and scholars who are selected and mentored by a permanent Faculty, each of whom are preeminent leaders in their fields. Among present and past Faculty and Members there have been 35 Nobel Laureates, 44 of the 62 Fields Medalists, and 23 of the 26 Abel Prize Laureates, as well as many MacArthur Fellows and Wolf Prize winners.

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April 30, 2021

Researchers discover the mechanism that likely generates huge white dwarf magnetic fields

by Peter Thorley, University of Warwick

A dynamo mechanism could explain the incredibly strong magnetic fields in white dwarf stars according to an international team of scientists, including a University of Warwick astronomer.

One of the most striking phenomena in astrophysics is the presence of magnetic fields. Like the Earth, stars and stellar remnants such as white dwarfs have one. It is known that the magnetic fields of white dwarfs can be a million times stronger than that of the Earth. However, their origin has been a mystery since the discovery of the first magnetic white dwarf in the 1970s. Several theories have been proposed, but none of them has been able to explain the different occurrence rates of magnetic white dwarfs, both as individual stars and in different binary star environments.

This uncertainty may be resolved thanks to research by an international team of astrophysicists, including Professor Boris Gänsicke from the University of Warwick and led by Professor Dr. Matthias Schreiber from Núcleo Milenio de Formación Planetaria at Universidad Santa María in Chile. The team showed that a dynamo mechanism similar to the one that generates magnetic fields on Earth and other planets can work in white dwarfs, and produce much stronger fields. This research, part-funded by the Science and Technology Facilities Council (STFC) and the Leverhulme Trust, has been published in the prestigious scientific journal Nature Astronomy .

Professor Boris Gänsicke of the Department of Physics at the University of Warwick said: "We have known for a long time that there was something missing in our understanding of magnetic fields in white dwarfs, as the statistics derived from the observations simply did not make sense. The idea that, at least in some of these stars, the field is generated by a dynamo can solve this paradox. Some of you may remember dynamos on bicycles: turning a magnet produces electric current . Here, it works the other way around, the motion of material leads to electric currents, which in turn generate the magnetic field."

According to the proposed dynamo mechanism, the magnetic field is generated by electric currents caused by convective motion in the core of the white dwarf. These convective currents are caused by heat escaping from the solidifying core.

"The main ingredient of the dynamo is a solid core surrounded by a convective mantle—in the case of the Earth, it is a solid iron core surrounded by convective liquid iron. A similar situation occurs in white dwarfs when they have cooled sufficiently," explains Matthias Schreiber.

The astrophysicist explains that at the beginning, after the star has ejected its envelope, the white dwarf is very hot and composed of liquid carbon and oxygen. However, when it has sufficiently cooled, it begins to crystallize in the center and the configuration becomes similar to that of the Earth: a solid core surrounded by a convective liquid. "As the velocities in the liquid can become much higher in white dwarfs than on Earth, the generated fields are potentially much stronger. This dynamo mechanism can explain the occurrence rates of strongly magnetic white dwarfs in many different contexts, and especially those of white dwarfs in binary stars" he says.

Thus, this research could solve a decades-old problem. "The beauty of our idea is that the mechanism of magnetic field generation is the same as in planets. This research explains how magnetic fields are generated in white dwarfs and why these magnetic fields are much stronger than those on Earth. I think it is a good example of how an interdisciplinary team can solve problems that specialists in only one area would have had difficulty with," Schreiber adds.

The next steps in this research, says the astrophysicist, are to perform a more detailed model of the dynamo mechanism and to test observationally the additional predictions of this model.

Journal information: Nature Astronomy

Provided by University of Warwick

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White dwarf stars.

Pushing the limits of its powerful vision, NASA’s Hubble Space Telescope uncovered the oldest burned-out stars in our Milky Way Galaxy. These extremely old, dim “clockwork stars” provide a completely independent reading on the age of the universe. The ancient white dwarf stars, as seen by Hubble, are 12-13 billion years old. Because earlier Hubble observations show that the first stars formed less than 1 billion years after the universe’s birth in the big bang, finding the oldest stars puts astronomers well within arm’s reach of calculating the absolute age of the universe. Though previous Hubble research sets the age of the universe at 13-14 billion years based on the rate of expansion of space, the universe’s birthday is such a fundamental and profound value that astronomers have long sought other age-dating techniques to cross-check their conclusions. Globular clusters are the first pioneer settlers of the Milky Way. Many coalesced to build the hub of our galaxy and formed billions of years before the appearance of the Milky Way’s magnificent pinwheel disk. Today 150 globular clusters survive in the galactic halo. The globular cluster M4 was selected because it is the nearest to Earth, so the intrinsically feeblest white dwarfs are still apparently bright enough to be picked out by Hubble. Image credit: NASA and H. Richer (University of British Columbia)

White Dwarf Stars

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• Detlev Koester 3  

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White dwarfs are the final stage for more than 95% of all stars. Their population statistics and properties contain a wealth of information about the history of star formation in our galaxy, the ages of stellar systems, and the relation between original mass at birth and that of the final remnant. They are also interesting individually as laboratories for physical conditions not easily reached in terrestrial labs: macroscopic manifestation of the Pauli principle, high densities and pressures, and extremely high magnetic fields. After a brief introduction with some historical milestones the observational status is reviewed: spectroscopic classification, determination of stellar parameters from spectroscopic and photometric observations, effective temperatures, surface gravities, radii, and masses. The next sections deal with the physics of the interior and evolution of white dwarfs, leading to the mass–radius relation and cooling times. Going back closer to the observations again, the physical processes in the outer layers are discussed: gravitational separation, diffusion, radiative levitation, accretion, and convective mixing. This leads to a review of our current understanding of the origin of spectral types and their interrelation. A final section gives brief introductions to topics at the center of current research: white dwarfs in open and globular clusters, debris disks, the origin of accreted metals in the atmospheres, magnetic fields and their origin, variable white dwarfs, and white dwarfs in binaries. This chapter was finished in February 2010 and reflects the status of knowledge at that time.

Keywords : Accretion, Chandrasekhar mass, Convective mixing, Debris disks, Gravitational settling, Initial–final mass relation, Magnetic fields, Mass–radius relation, Stellar remnants, White dwarfs

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Althaus, L. G., Garcia-Berro, E., Isern, J., Córsico, A. H., & Rohrmann, R. D. 2007, A&A, 465, 249

ADS   Google Scholar  

Althaus, L. G., Panei, J. A., Miller Bertolami, M. M., García-Berro, E., Córsico, A. H., Romero, A. D., Kepler, S. O., & Rohrmann, R. D. 2009, ApJ, 704, 1605

Althaus, L. G., Serenelli, A. M., Córsico, A. H., & Benvenuto, O. G. 2002, MNRAS, 330, 685

Augusteijn, T., Greimel, R., van den Besselaar, E. J. M., Groot, P. J., & Morales-Rueda, L. 2008, A&A, 486, 843

Barstow, M. A., Bond, H. E., Burleigh, M. R., & Holberg, J. B. 2001, MNRAS, 322, 891

Barstow, M. A., Bond, H. E., Holberg, J. B., Burleigh, M. R., Hubeny, I., & Koester, D. 2005, MNRAS, 362, 1134

Barstow, M. A., Good, S. A., Holberg, J. B., Hubeny, I., Bannister, N. P., Bruhweiler, F. C., Burleigh, M. R., & Napiwotzki, R. 2003, MNRAS, 341, 870

Bedin, L. R., Salaris, M., Piotto, G., Anderson, J., King, I. R., & Cassisi, S. 2009, ApJ, 697, 965

Benvenuto, O. G., Althaus, L. G., & Torres, D. F. 1999, MNRAS, 305, 905

Berger, L., Koester, D., Napiwotzki, R., Reid, I. N., & Zuckerman, B. 2005, A&A, 444, 565

Bergeron, P., Leggett, S. K., & Ruiz, M. T. 2001, ApJS, 133, 413

Bergeron, P., Wesemael, F., Fontaine, G., & Liebert, J. 1990, ApJ, 351, L21

Bergeron, P., Wesemael, F., Lamontagne, R., Fontaine, G., Saffer, R. A., & Allard, N. F. 1995, ApJ, 449, 258

Böhm-Vitense, E. 1958, Zeitschrift für Astrophysik, 46, 108

Bondi, H. 1952, MNRAS, 112, 195

MathSciNet   ADS   Google Scholar  

Brassard, P., & Fontaine, G. 1998, J R Astron Soc Can, 92, 315

Castanheira, B. G., & Kepler, S. O. 2009, MNRAS, 396, 1709

Catalán, S., Isern, J., García-Berro, E., & Ribas, I. 2008, MNRAS, 387, 1693

Chabrier, G., Brassard, P., Fontaine, G., & Saumon, D. 2000, ApJ, 543, 216

Chandrasekhar, S. 1939, An Introduction to the Study of Stellar Structure (Chicago, Il: The University of Chicago Press)

Google Scholar  

Chayer, P., Fontaine, G., & Wesemael, F. 1995a, ApJS, 99, 189

Chayer, P., Vennes, S., Pradhan, A. K., Thejll, P., Beauchamp, A., Fontaine, G., & Wesemael, F. 1995b, ApJ, 454, 429

D’Antona, F., & Mazzitelli, I. 1979, A&A, 74, 161

Davis, D. S., Richer, H. B., Rich, R. M., Reitzel, D. R., & Kalirai, J. S. 2009, ApJ, 705, 398

Debes, J. H., & Sigurdsson, S. 2002, ApJ, 572, 556

Dobbie, P. D., Napiwotzki, R., Burleigh, M. R., Williams, K. A., Sharp, R., Barstow, M. A., Casewell, S. L., & Hubeny, I. 2009, MNRAS, 395, 2248

Dominguez, I., Chieffi, A., Limongi, M., & Straniero, O. 1999, ApJ, 524, 226

Dufour, P., Fontaine, G., Liebert, J., Schmidt, G. D., & Behara, N. 2008, ApJ, 683, 978

Dupuis, J., Fontaine, G., Pelletier, C., & Wesemael, F. 1992, ApJS, 82, 505

Dupuis, J., Fontaine, G., Pelletier, C., & Wesemael, F. 1993a, ApJS, 84, 73

Dupuis, J., Fontaine, G., & Wesemael, F. 1993b, ApJS, 87, 345

Edgar, R. 2004, New Astro Rev, 48, 843

Eisenstein, D. J., et al. 2006, AJ, 132, 676

Farihi, J., Barstow, M. A., Redfield, S., Dufour, P., & Hambly, N. C. 2010, ArXiv e-print 1001.5025

Farihi, J., Jura, M., & Zuckerman, B. 2009, ApJ, 694, 805

Farihi, J., Zuckerman, B., & Becklin, E. E. 2008, ApJ, 674, 431

Ferrario, L., & Wickramasinghe, D. T. 2005, MNRAS, 356, 615

Fontaine, G., & Brassard, P. 2008, PASP, 120, 1043

Fontaine, G., Brassard, P., & Bergeron, P. 2001, PASP, 113, 409

Fontaine, G., Brassard, P., & Charpinet, S. 2003, Ap&SS, 284, 257

Fontaine, G., & Michaud, G. 1979, ApJ, 231, 826

Fontaine, G., Villeneuve, B., & Wilson, J. 1981, ApJ, 243, 550

Fontaine, G., & Wesemael, F. 1987, in Conference on Faint Blue Stars, 2nd, Tucson, AZ, June 1–5, 1987, Proceedings Schenectady (New York: L. Davis Press, Inc.), pp 319–326. Discussion, pp 327, 328

Gänsicke, B. T., Koester, D., Girven, J., Marsh, T. R., & Steeghs, D. 2010, Science, 327, 188

Gänsicke, B. T., Marsh, T. R., Southworth, J., & Rebassa-Mansergas, A. 2006, Science, 314, 1908

Gatewood, G., & Han, I. 2006, AJ, 131, 1015

Hamada, T., & Salpeter, E. E. 1961, ApJ, 134, 683

Hansen, B. 2004, Phys Rep, 399, 1

Hansen, B. M. S., & Liebert, J. 2003, ARA&A, 41, 465

Holberg, J. B. 2009, J Phys Conf Ser, 172, 012022

Holberg, J. B., Sion, E. M., Oswalt, T., McCook, G. P., Foran, S., & Subasavage, J. P. 2008, AJ, 135, 1225

Iben, I., Jr., Kaler, J. B., Truran, J. W., & Renzini, A. 1983, ApJ, 264, 605

Isern, J., Mochkovitch, R., Garcia-Berro, E., & Hernanz, M. 1997, ApJ, 485, 308

Jeffery, E. J., von Hippel, T., Jefferys, W. H., Winget, D. E., Stein, N., & De Gennaro, S. 2007, ApJ, 658, 391

Jordan, S. 2009, in Cosmic Magnetic Fields: From Planets, to Stars and Galaxies, Proceedings IAU Symposium No. 259, eds. K.G. Strassmeier, A.G. Kosovichev & J. Beckman, 369

Jordan, S., et al. 1998, A&A, 330, 277

Jura, M. 2003, ApJ, 584, L91

Jura, M., Muno, M. P., Farihi, J., & Zuckerman, B. 2009, ApJ, 699, 1473

Kalirai, J. S., Richer, H. B., Reitzel, D., Hansen, B. M. S., Rich, R. M., Fahlman, G. G., Gibson, B. K., & von Hippel, T. 2005, ApJ, 618, L123

Kalirai, J. S., Saul Davis, D., Richer, H. B., Bergeron, P., Catelan, M., Hansen, B. M. S., & Rich, R. M. 2009, ApJ, 705, 408

Karl, C. A., Napiwotzki, R., Heber, U., Dreizler, S., Koester, D., & Reid, I. N. 2005, A&A, 434, 637

Kilic, M., von Hippel, T., Leggett, S. K., & Winget, D. E. 2006, ApJ, 646, 474

Kitsikis, A., Fontaine, G., & Brassard, P. 2005, in ASP Conf. Ser. 334, 14th European workshop on white dwarfs, eds. D. Koester & S. Moehler (San Francisco: ASP), 65

Klein, B., Jura, M., Koester, D., Zuckerman, B., & Melis, C. 2010, ApJ, 709, 950

Knox, R. A., Hawkins, M. R. S., & Hambly, N. C. 1999, MNRAS, 306, 736

Koester, D. 1976, A&A, 52, 415

Koester, D. 1987, ApJ, 322, 852

Koester, D. 2009, A&A, 498, 517

Koester, D., & Chanmugam, G. 1990, Rep Prog Phys, 53, 837–915

Koester, D., & Reimers, D. 1981, A&A, 99, L8

Koester, D., Voss, B., Napiwotzki, R., Christlieb, N., Homeier, D., Lisker, T., Reimers, D., & Heber, U. 2009, A&A, 505, 441

Koester, D., Weidemann, V., & Zeidler, E. 1982, A&A, 116, 147

Koester, D., & Wilken, D. 2006, A&A, 453, 1051

Külebi, B., Jordan, S., Euchner, F., Gänsicke, B. T., & Hirsch, H. 2009, A&A, 506, 1341

Lamb, D. Q., & van Horn, H. M. 1975, ApJ, 200, 306

Lamb, D. Q. J. 1974, PhD thesis, University of Rochester

Landenberger-Schuh, S. 2005, PhD thesis, University of Tübingen

Landolt, A. U. 1968, ApJ, 153, 151

Layden, A. C., Sarajedini, A., von Hippel, T., & Cool, A. M. 2005, ApJ, 632, 266

Leggett, S. K., Ruiz, M. T., & Bergeron, P. 1998, ApJ, 497, 294

Liebert, J. 1976, ApJ, 210, 715

Liebert, J. 1988, PASP, 100, 1302

Liebert, J., Bergeron, P., & Holberg, J. B. 2005a, ApJS, 156, 47

Liebert, J., Young, P. A., Arnett, D., Holberg, J. B., & Williams, K. A. 2005b, ApJ, 630, L69

Liebert, J., et al. 2005c, AJ, 129, 2376

Liebert, J., Fontaine, G., & Wesemael, F. 1987, MemSAIt, 58, 17

Liebert, J., Wesemael, F., Hansen, C. J., Fontaine, G., Shipman, H. L., Sion, E. M., Winget, D. E., & Green, R. F. 1986, ApJ, 309, 241

Macdonald, J., & Vennes, S. 1991, ApJ, 371, 719

Michaud, G., Charland, Y., Vauclair, S., & Vauclair, G. 1976, ApJ, 210, 447

Miller Bertolami, M. M., Althaus, L. G., Serenelli, A. M., & Panei, J. A. 2006, A&A, 449, 313

Monelli, M., et al. 2005, ApJ, 621, L117

Montgomery, M. H., Klumpe, E. W., Winget, D. E., & Wood, M. A. 1999, ApJ, 525, 482

Mullally, F., Kilic, M., Reach, W. T., Kuchner, M. J., von Hippel, T., Burrows, A., & Winget, D. E. 2007, ApJS, 171, 206

Napiwotzki, R., et al. 2001, Astronomische Nachrichten, 322, 411

Napiwotzki, R., et al. 2007, in ASP Conf. Ser. 372, 15th European workshop on white dwarfs, eds. R. Napiwotzki & M. R. Burleigh (San Francisco: ASP), 387

Panei, J. A., Althaus, L. G., & Benvenuto, O. G. 2000, A&A, 353, 970

Panei, J. A., Althaus, L. G., Chen, X., & Han, Z. 2007, MNRAS, 382, 779

Paquette, C., Pelletier, C., Fontaine, G., & Michaud, G. 1986a, ApJS, 61, 177

Paquette, C., Pelletier, C., Fontaine, G., & Michaud, G. 1986b, ApJS, 61, 197

Parthasarathy, M., Branch, D., Jeffery, D. J., & Baron, E. 2007, New Astron Rev, 51, 524

Pelletier, C., Fontaine, G., Wesemael, F., Michaud, G., & Wegner, G. 1986, ApJ, 307, 242

Provencal, J. L., Shipman, H. L., Koester, D., Wesemael, F., & Bergeron, P. 2002, ApJ, 568, 324

Pyrzas, S., et al. 2009, MNRAS, 394, 978

Rebassa-Mansergas, A., Gänsicke, B. T., & Koester, D. 2009, J Phys Conf Ser, 172, 012025

Reid, I. N. 1996, AJ, 111, 2000

Reid, I. N. 2005, ARA&A, 43, 247

Romanishin, W., & Angel, J. R. P. 1980, ApJ, 235, 992

Salpeter, E. E. 1961, ApJ, 134, 669

Saumon, D., Chabrier, G., & van Horn, H. M. 1995, ApJS, 99, 713

Schatzman, E. 1945, AnAp, 8, 143

Schmidt, G. D., & Smith, P. S. 1994, ApJ, 423, L63

Schmidt, G. D., et al. 2003, ApJ, 595, 1101

Segretain, L., Chabrier, G., Hernanz, M., Garcia-Berro, E., Isern, J., & Mochkovitch, R. 1994, ApJ, 434, 641

Serenelli, A. M., Althaus, L. G., Rohrmann, R. D., & Benvenuto, O. G. 2002, MNRAS, 337, 1091

Shipman, H. L., Provencal, J. L., Hog, E., & Thejll, P. 1997, ApJ, 488, L43

Silvestri, N. M., et al. 2007, AJ, 134, 741

Sion, E. M. 1984, ApJ, 282, 612

Sion, E. M., Greenstein, J. L., Landstreet, J. D., Liebert, J., Shipman, H. L., & Wegner, G. A. 1983, ApJ, 269, 253

Sion, E. M., Holberg, J. B., Oswalt, T. D., McCook, G. P., & Wasatonic, R. 2009, AJ, 138, 1681

Steinfadt, J. D. R., Bildsten, L., & Howell, S. B. 2008, ApJ, 677, L113

Strand, K. A., & Kallarkal, V. V. 1989, in Lecture Notes in Physics, Vol. 328, ed. G. Wegner (Berlin: Springer Verlag), pp 413–415. IAU Colloq. 114: White Dwarfs

Sweeney, M. A. 1976, A&A, 49, 375

Tassoul, M., Fontaine, G., & Winget, D. E. 1990, ApJS, 72, 335

Tinsley, B. M. 1974, PASP, 86, 554

Tout, C. A., Wickramasinghe, D. T., Liebert, J., Ferrario, L., & Pringle, J. E. 2008, MNRAS, 387, 897

Tremblay, P., & Bergeron, P. 2008, ApJ, 672, 1144

Unglaub, K. 2008, A&A, 486, 923

van Altena, W. F., Lee, J. T., & Hoffleit, D. 1995a, VizieR Online Data Catalog, 1174, 0

van Altena, W. F., Lee, J. T., & Hoffleit, E. D. 1995b, The General Catalogue of Trigonometric [Stellar] Paralaxes (New Haven, CT: Yale University Observatory). —c1995, 4th ed., completely revised and enlarged

van den Heuvel, E. P. J. 1975, ApJ, 196, L121

Vanlandingham, K. M., et al. 2005, AJ, 130, 734

Vauclair, G., & Reisse, C. 1977, A&A, 61, 415

Vauclair, G., Vauclair, S., & Greenstein, J. L. 1979, A&A, 80, 79

Vennes, S. 1999, ApJ, 525, 995

von Hippel, T., Kuchner, M. J., Kilic, M., Mullally, F., & Reach, W. T. 2007, ApJ, 662, 544

Voss, B., Koester, D., Napiwotzki, R., Christlieb, N., & Reimers, D. 2007, A&A, 470, 1079

Wegner, G., & Reid, I. N. 1991, ApJ, 375, 674

Weidemann, V. 1977, A&A, 59, 411

Werner, K., & Herwig, F. 2006, PASP, 118, 183

Wesemael, F., Greenstein, J. L., Liebert, J., Lamontagne, R., Fontaine, G., Bergeron, P., & Glaspey, J. W. 1993, PASP, 105, 761

Wickramasinghe, D. T., & Ferrario, L. 2000, PASP, 112, 873

Wickramasinghe, D. T. 2005, MNRAS, 356, 1576

Wickramasinghe, D. T., Schmidt, G., Ferrario, L., & Vennes, S. 2002, MNRAS, 332, 29

Winget, D. E., Hansen, C. J., Liebert, J., van Horn, H. M., Fontaine, G., Nather, R. E., Kepler, S. O., & Lamb, D. Q. 1987, ApJ, 315, L77

Winget, D. E., & Kepler, S. O. 2008, ARA&A, 46, 157

Winget, D. E., Kepler, S. O., Campos, F., Montgomery, M. H., Girardi, L., Bergeron, P., & Williams, K. 2009, ApJ, 693, L6

Wood, M. A. 1995, in White Dwarfs, Proceedings of the 9th European Workshop on White Dwarfs (Berlin/Heidelberg/New York: Springer-Verlag) XII, 348. Also Lecture Notes in Physics, Vol. 443, eds. D. Koester & K. Werner, 51

Yakovlev, D. G., Kaminker, A. D., Gnedin, O. Y., & Haensel, P. 2001, Phys Rep, 354, 1

Zuckerman, B. 2001, ARA&A, 39, 549

Zuckerman, B., & Becklin, E. E. 1987, Nature, 330, 138

Zuckerman, B., Koester, D., Melis, C., Hansen, B. M., & Jura, M. 2007, ApJ, 671, 872

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Koester, D. (2013). White Dwarf Stars. In: Oswalt, T.D., Barstow, M.A. (eds) Planets, Stars and Stellar Systems. Springer, Dordrecht. https://doi.org/10.1007/978-94-007-5615-1_11

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