Unsolved:Hypothetical star
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Short description: Star types predicted by theory
A hypothetical star is a star, or type of star, that is speculated to exist but has yet to be definitively observed. Hypothetical types of stars have been conjectured to exist, have existed, or will exist in the future universe.[1][2][3]
Types
Scientifically speculated hypothetical types include:
| Type | Description | Candidates | Notes | Citations |
|---|---|---|---|---|
| Anti-star | A star composed of antimatter. | Anti-helium nuclei have been detected. | [4][5] | |
| Blitzar | Pulsar with enough mass to suddenly collapse into a black hole when the rotation speed slows. | [6] | ||
| Blue dwarf | Conjectured to develop after a red dwarf has exhausted most of its hydrogen. | N/A | The visible universe is not old enough for this form to come into existence. | [7] |
| Black dwarf | The final state for a star, like the Sun, that is too small to become a black hole or a neutron star. It would take a star like the Sun roughly a quadrillion (1015) years to reach this state, so none are believed to exist today. | N/A | The universe is not old enough for this form to come into existence. | [1][8] |
| Black star | A star predicted in semiclassical gravity which collapses into a black hole state but has neither a gravitational singularity nor an event horizon. | none | [9] | |
| Boson star | A star or astronomical object made of bosons, such as photons or gluons, rather than conventional matter. | none | [10][2] | |
| Buchdahl star | A stellar object at the upper bound on compactness. | none | [11] | |
| Dark energy star | A conjectured alternative to a black hole. | none | [12] | |
| Dark matter star | Conjectured to have existed early in the universe. | JADES-GS-z13-0, JADES-GS-z12-0, and JADES-GS-z11-0 | [1][2] | |
| Dark star | A theoretical construct based on Newtonian gravitation, of a star with gravity so strong that even light cannot escape. | N/A | This form cannot exist, as Newtonian gravitation breaks down under these conditions. It is a disproved hypothesis. | [citation needed] |
| Electroweak star | A star where gravitational collapse is prevented by radiation pressure resulting from electroweak burning. In this type of star, quarks are converted to leptons via the electroweak interaction. The core of the star would be hand-sized, containing perhaps two Earth masses, and might follow from the collapse of a quark star. | none | [13] | |
| Frozen star | A very-low-mass star with a surface temperature of perhaps 300 kelvins that could form in the far future, when the metallicity of the interstellar medium is higher than the current value. | N/A | The universe is not old enough for this form to come into existence. | [14] |
| Fuzzball | A formulation of black holes in string theory. | none | [15] | |
| Gravastar | An alternative to a black hole that denies the possibility of a singularity. | none | [16] | |
| Hawking star | A star that contains a microscopic primordial black hole (PBH) in its core | none | [17] | |
| Hyperon star | A massive neutron star containing hyperons. | PSR J0348+0432 | [18][19] | |
| Iron star | A final state for a star in the far future (101500 years) of the universe, when all matter is transmuted to iron via quantum tunneling. | N/A | The universe is not old enough for this form to come into existence. | [8] |
| MECO | Magnetospheric eternally collapsing object: a hypothetical alternative to black holes. | Q0957+561 | [20] | |
| Planck star | A star where the energy density is around the Planck density. The star will start to expand as soon as its density reaches the Planck constant. To the black hole, it expands instantly, but to the outside world, it takes eons to expand even the slightest. | none | [21] | |
| Population III star | The very earliest stars, virtually free of metals, believed to have existed in the early universe when the only common elements were primordial hydrogen and helium. | none | [22][1] | |
| Preon star | A star with a core composed of preons. | none | [23] | |
| Q star (grey hole) | A compact, heavy neutron star with an exotic state of matter where most light does not escape the star. | Cygnus X-1 | [24] | |
| Quark star | Star composed of quark matter or strange matter. | 3C 58, PSR B0943+10, XTE J1739-285 | [2][1][25] | |
| Quasi-star | A conjectured star from the early universe with a black hole at its center. | The Cliff, MoM-BH*-1[26] | [27] | |
| Strange star | A form of quark star, a neutron star with strange matter at its core, or star which is a ball of strange matter. | none | [28] | |
| Thorne–Żytkow object | A hybrid red giant, red supergiant, or Wolf–Rayet star whose core is a neutron star. | HV 11417 | [2][29] | |
| White hole | The polar opposite of a black hole, it ejects matter from its core into space. It is hypothetically formed when a region around a black hole experiences a loss in entropy, and will immediately collapse when the entropy is restored. The loss of entropy allows the black hole to travel back in time, so it will continue to suck matter up into its event horizon, but once one goes into the event horizon of a white hole, space-time is so distorted that it will always lead one to outside the event horizon, even if one tries to go to the singularity. | GRB 060614 | [30] |
Specific stars
Specific hypothetical stars include:
| Star | Description | Notes | Citations |
|---|---|---|---|
| Nemesis | A star proposed as a companion to the Sun by Richard A. Muller in 1984 | This star was ruled out by all-sky surveys.[31] | [32] |
| Coatlicue | A star thought to be the reason for how the Sun (and many other stars) came to be, proposed by Matthieu Gounelle and Georges Meynet in 2012 | [33][34] | |
| 3 Cassiopeiae | A star recorded by astronomer John Flamsteed, but never seen again | [35] | |
| 34 Tauri | A star recorded by John Flamsteed, later revealed to have been the planet Uranus | [36] |
See also
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Pearson, Ezzy (June 3, 2025). "5 hypothetical stars we've yet to discover". BBC Sky an Night Magazine. https://www.skyatnightmagazine.com/space-science/hypothetical-stars-astronomers-have-yet-to-discover.
- ↑ 2.0 2.1 2.2 2.3 2.4 Betz, Eric (March 25, 2021). "Four crazy stars astronomers think might really exist". Astronomy Magazine. https://www.astronomy.com/science/four-crazy-stars-astronomers-think-might-really-exist/.
- ↑ Wenz, John (January 18, 2019). "Four Types of Stars That Will Not Exist for Billions or Even Trillions of Years". Smithsonian Magazine. https://www.smithsonianmag.com/science-nature/four-types-stars-will-not-exist-billions-or-even-trillions-years-180971299/.
- ↑ "Are There Anti-Stars (Made of Antimatter) Around Us?". SciTechDaily. July 10, 2022. https://scitechdaily.com/are-there-anti-stars-made-of-antimatter-around-us/.
- ↑ Dupourqué, Simon (April 20, 2021). "Constraints on the antistar fraction in the Solar System neighborhood from the 10-year Fermi Large Area Telescope gamma-ray source catalog". Physical Review D 103. doi:10.1103/PhysRevD.103.083016.
- ↑ Ravi, Vikram; Lasky, Paul D. (July 2014). "The birth of black holes: neutron star collapse times, gamma-ray bursts and fast radio bursts". Monthly Notices of the Royal Astronomical Society 441 (3): 2433–2439. doi:10.1093/mnras/stu720. Bibcode: 2014MNRAS.441.2433R.
- ↑ Adams, F. C.; Graves, G. J. M.; Laughlin, G. (December 2004). "Red Dwarfs and the End of the Main Sequence". in García-Segura, G.; Tenorio-Tagle, G.; Franco, J. et al.. Gravitational Collapse: From Massive Stars to Planets. 22. pp. 46–49. Bibcode: 2004RMxAC..22...46A.
- ↑ 8.0 8.1 Caplan, M. E. (2020). "Black Dwarf Supernova in the Far Future". Monthly Notices of the Royal Astronomical Society 497 (4): 4357–4362. doi:10.1093/mnras/staa2262. Bibcode: 2020MNRAS.497.4357C.
- ↑ Barceló, Carlos (October 2009). "Black Stars, Not Holes". Scientific American 301 (4): 38–45. doi:10.1038/scientificamerican1009-38. Bibcode: 2009SciAm.301d..38B.
- ↑ Alcubierre, Miguel (February 2023). "Boson stars and their relatives in semiclassical gravity". Physical Review D 107 (4): id. 045017. doi:10.1103/PhysRevD.107.045017. Bibcode: 2023PhRvD.107d5017A.
- ↑ Chakrabarti, Soumya (April 2026). "On the stability of the objects of limiting compactness: Black hole and Buchdahl star". Physics Letters B (Elsevier) 875. doi:10.1016/j.physletb.2026.140333.
- ↑ Banerjee, Ayan (March 2020). "Analytical model of dark energy stars". Modern Physics Letters A 35 (10): id. 2050071. doi:10.1142/S0217732320500716. Bibcode: 2020MPLA...3550071B.
- ↑ Dai, De-Chang (December 2010). "Electroweak stars: how nature may capitalize on the standard model's ultimate fuel". Journal of Cosmology and Astroparticle Physics 2010. doi:10.1088/1475-7516/2010/12/004. Bibcode: 2010JCAP...12..004D.
- ↑ Beech, Martin (March 28, 2019). Introducing the Stars: Formation, Structure and Evolution. Springer. p. 166. ISBN 9783030117047.
- ↑ Guo, Bin (July 2018). "Can we observe fuzzballs or firewalls?". Journal of High Energy Physics 2018 (7): id. 162. doi:10.1007/JHEP07(2018)162. Bibcode: 2018JHEP...07..162G.
- ↑ Ray, Saibal (2020). "Gravastar: An alternative to black hole". International Journal of Modern Physics D 29 (5): id. 2030004-260. doi:10.1142/S0218271820300049. Bibcode: 2020IJMPD..2930004R.
- ↑ Santarelli, Andrew D. (December 2024). "Formation of Sub-Chandrasekhar-mass Black Holes and Red Stragglers via Hawking Stars in Ultrafaint Dwarf Galaxies". The Astrophysical Journal 977 (2): id. 145. doi:10.3847/1538-4357/ad8ec0. Bibcode: 2024ApJ...977..145S.
- ↑ Zhao, Xian-Feng (2017). "Can the massive neutron star PSR J0348+0432 be a hyperon star?". Acta Physica Polonica B 48 (2): 171. doi:10.5506/APhysPolB.48.171. ISSN 0587-4254. Bibcode: 2017AcPPB..48..171Z.
- ↑ Zhao, Xian-Feng (December 23, 2017). "The hyperons in the massive neutron star PSR J0348+0432". Chinese Journal of Physics 53 (4): 221–234. doi:10.6122/CJP.20150601D.
- ↑ Robertson, Stanley L.; Leiter, Darryl J. (2006). "The Magnetospheric Eternally Collapsing Object (MECO) Model of Galactic Black Hole Candidates and Active Galactic Nuclei". in Kreitler, Paul V.. New Developments in Black Hole Research. New York, NY USA: Nova Science Publishers, Inc.. p. 1. ISBN 1-59454-641-X. Bibcode: 2006ndbh.book....1R.
- ↑ Barrau, Aurélien; Rovelli, Carlo (December 2014). "Planck star phenomenology". Physics Letters B 739: 405–409. doi:10.1016/j.physletb.2014.11.020. Bibcode: 2014PhLB..739..405B.
- ↑ Fraser, M. (June 2017). "The mass distribution of Population III stars". Monthly Notices of the Royal Astronomical Society 468 (1): 418–425. doi:10.1093/mnras/stx480. Bibcode: 2017MNRAS.468..418F.
- ↑ Hansson, J.; Sandin, F. (June 2005). "Preon stars: a new class of cosmic compact objects". Physics Letters B 616 (1–2): 1–7. doi:10.1016/j.physletb.2005.04.034. Bibcode: 2005PhLB..616....1H.
- ↑ Brecher, K. (May 1993). "Gray Holes". Bulletin of the American Astronomical Society. American Astronomical Society, 182nd AAS Meeting, #55.07 25: 89. Bibcode: 1993AAS...182.5507B.
- ↑ Weber, Fridolin (March 2013). "Structure of Quark Stars". Proceedings of the International Astronomical Union 291: 61–66. doi:10.1017/S1743921312023174. Bibcode: 2013IAUS..291...61W.
- ↑ Naidu, Rohan P. et al. (August 2026). "A gas-enshrouded and gas-reddened black hole at cosmic dawn" (in en). Nature 656 (8127): 329–333. doi:10.1038/s41586-026-10846-4. ISSN 1476-4687. PMID 42587117.
- ↑ Begelman, Mitchell C. (July 2008). "Quasi-stars: accreting black holes inside massive envelopes". Monthly Notices of the Royal Astronomical Society 387 (4): 1649–1659. doi:10.1111/j.1365-2966.2008.13344.x. Bibcode: 2008MNRAS.387.1649B.
- ↑ Yang, Shuhua (April 2023). "Confronting Strange Stars with Compact-Star Observations and New Physics". Universe 9 (5): id. 202. doi:10.3390/universe9050202. Bibcode: 2023Univ....9..202Y.
- ↑ "Stars with degenerate neutron cores. I – Structure of equilibrium models". The Astrophysical Journal 212 (1): 832–858. March 15, 1977. doi:10.1086/155109. Bibcode: 1977ApJ...212..832T.
- ↑ Bianchi, Eugenio (November 2018). "White holes as remnants: a surprising scenario for the end of a black hole". Classical and Quantum Gravity 35 (22): id. 225003. doi:10.1088/1361-6382/aae550. Bibcode: 2018CQGra..35v5003B.
- ↑ Whitmire, Daniel P. (January 2016). "Periodic mass extinctions and the Planet X model reconsidered". Monthly Notices of the Royal Astronomical Society: Letters 455 (1): L114–L117. doi:10.1093/mnrasl/slv157. Bibcode: 2016MNRAS.455L.114W.
- ↑ Muller, R. A. (August 1984). "Evidence for a solar companion star: recent developments" (PDF). International Astronomical Union symposium on the search for extraterrestrial life. 112. Boston, MA. http://www.lepouvoirmondial.com/media/02/02/4036119153.pdf. Retrieved 2026-08-16.
- ↑ Gounelle, M.; Meynet, G. (2012). "Solar system genealogy revealed by extinct short-lived radionuclides in meteorites". Astronomy & Astrophysics 545: A4. doi:10.1051/0004-6361/201219031. Bibcode: 2012A&A...545A...4G.
- ↑ Gounelle, Matthieu (October 2015). "The abundance of 26Al-rich planetary systems in the Galaxy". Astronomy & Astrophysics 582: id. A26. doi:10.1051/0004-6361/201526174. Bibcode: 2015A&A...582A..26G.
- ↑ Ashworth, William B. (February 1980). "A Probable Flamsteed Observation of the Cassiopeia A Supernova" (in en). Journal for the History of Astronomy 11 (1): 1–9. doi:10.1177/002182868001100102. ISSN 0021-8286. Bibcode: 1980JHA....11....1A.
- ↑ Sheehan, William, ed (2021). Neptune: From Grand Discovery to a World Revealed: Essays on the 200th Anniversary of the Birth of John Couch Adams. Springer Nature. p. 50. ISBN 978-3-030-54218-4. https://books.google.com/books?id=vaQvEAAAQBAJ&pg=PA50.
Further reading
- Schunck, F.E. and E.W. Mielke: "General relativistic boson stars", Class. Quantum. Grav. Vol. 20, R301 - R356 (2003)
