Quasi-star

"Black hole star" redirects here. For black holes created from stars, seeStellar black hole.For stars that become black holes, seeSupernova.For stars with black hole cores, seeHawking star.For types of stars denser than neutron stars, seeExotic star.For the 1994 Soundgarden song, seeBlack Hole Sun.

Not to be confused with a quasi-stellar object orquasar.

Size comparison of a hypothetical quasi-star to some of thelargest known stars.

A quasi-star rendered withCelestia

Aquasi-star(also calledblack hole star) is ahypothetical typeof extremelymassiveandluminousstarthat may have existed early in thehistory of the Universe.They are thought to live around 7-10 million years. Unlike modern stars, which are powered bynuclear fusionin their cores, a quasi-star'senergywould come from material falling into ablack holeat its core. They were first proposed in the 1960s and have since provided valuable insights into the earlyuniverse,galaxy formation, and the behavior ofblack holes.Although they have not been observed, they are considered to be a possible progenitor ofsupermassive black holes.

Formation and properties

A quasi-star would have resulted from the core of a largeprotostarcollapsing into ablack hole,where the outer layers of the protostar are massive enough to absorb the resulting burst of energy without being blown away or falling into the black hole, as occurs with modernsupernovae.Such a star would have to be at least 1,000solar masses(2.0×10³³kg).Quasi-stars may have also formed fromdark matter halosdrawing in enormous amounts of gas via gravity, which can producesupermassive starswith tens of thousands of solar masses.Formation of quasi-stars could only happen early in the development of the Universe before hydrogen and helium were contaminated by heavier elements; thus, they may have been very massivePopulation IIIstars.Such stars would dwarfVY Canis Majoris,UY Scuti,andStephenson 2 DFK 1also known asStephenson 2-18,three among thelargest known modern stars.

Once the black hole had formed at the protostar's core, it would continue generating a large amount ofradiant energyfrom the infall of stellar material. This constant outburst of energy would counteract the force ofgravity,creating an equilibrium similar to the one that supports modern fusion-based stars.Quasi-stars would have had a short maximum lifespan, approximately 7 million years,during which the core black hole would have grown to about 1,000–10,000 solar masses (2×10³³–2×10³⁴kg).Theseintermediate-mass black holeshave been suggested as the progenitors of modernsupermassive black holessuch asthe one in the center of the Galaxy.

Quasi-stars are predicted to have had surface temperatures higher than 10,000 K (9,700 °C).At these temperatures, each one would be about asluminousas a small galaxy.As a quasi-star cools over time, its outer envelope would become transparent, until further cooling to a limiting temperature of 4,000 K (3,730 °C).This limiting temperature would mark the end of the quasi-star's life since there is nohydrostatic equilibriumat or below this limiting temperature.The object would then quickly dissipate, leaving behind theintermediate mass black hole.

See also

• Accretion (astrophysics)– Accumulation of particles into a massive object by gravitationally attracting more matter
• Accretion disk– Structure formed by diffuse material in orbital motion around a massive central body
• Blitzar– Hypothetical type of neutron star
• Thorne–Żytkow object– Hypothetical hybrid star type
• Neutron star– Collapsed core of a massive star
• Direct collapse black hole– High-mass black hole seeds

Further reading

• Ball, Warrick H.; Tout, Christopher A.; Żytkow, Anna N.; Eldridge, John J. (2011). "The structure and evolution of quasi-stars".Monthly Notices of the Royal Astronomical Society.414(3): 2751–2762.arXiv:1102.5098.Bibcode:2011MNRAS.414.2751B.doi:10.1111/j.1365-2966.2011.18591.x.S2CID119239346.
• Ball, Warrick H. (2012). "Quasi-stars and the Schönberg-Chandrasekhar limit".arXiv:1207.5972.
• Czerny, Bozena; Janiuk, Agnieszka; Sikora, Marek; Lasota, Jean-Pierre (2012). "Quasi-Star Jets as Unidentified Gamma-Ray Sources".The Astrophysical Journal.755(1): L15.arXiv:1207.1560.Bibcode:2012ApJ...755L..15C.doi:10.1088/2041-8205/755/1/L15.S2CID113397287.
• Fiacconi, Davide; Rossi, Elena M. (2017). "Light or heavy supermassive black hole seeds: The role of internal rotation in the fate of supermassive stars".Monthly Notices of the Royal Astronomical Society.464(2): 2259–2269.arXiv:1604.03936.doi:10.1093/mnras/stw2505.
• Herrington, Nicholas P.; Whalen, Daniel J.; Woods, Tyrone E. (2023)."Modelling supermassive primordial stars with <SCP>mesa</SCP>".Monthly Notices of the Royal Astronomical Society.521:463–473.arXiv:2208.00008.doi:10.1093/mnras/stad572.
• Dotan, Calanit; Rossi, Elena M.; Shaviv, Nir J. (2011). "A lower limit on the halo mass to form supermassive black holes".Monthly Notices of the Royal Astronomical Society.417(4): 3035–3046.arXiv:1107.3562.Bibcode:2011MNRAS.417.3035D.doi:10.1111/j.1365-2966.2011.19461.x.

External links

• "Quasi-Stars: Black Holes at the Core of the Universe's Largest Stars".16 May 2020.
• Kurzgesagt,Black Hole Star – The Star That Shouldn't Exist