Hypothetical early-universe star with a black hole core
"Black hole star" redirects here. For black holes created from stars, seeStellar black hole. For stars that become black holes, seeSupernova. 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 type of extremely large andluminousstar that may have existed early in thehistory of the Universe. They are thought to have existed for around 7–10 million years due to their immensemass.[citation needed] Unlike modern stars, which are powered bynuclear fusion in their cores, a quasi-star'senergy would come from material falling into ablack hole at 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.[1]
A quasi-star would have resulted from the core of a largeprotostar collapsing 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 (2.0×1033 kg).[2] Quasi-stars may have also formed fromdark matter halos drawing in enormous amounts of gas via gravity, which can producesupermassive stars with tens of thousands of solar masses.[3][4] 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 III stars.[5] Such stars would dwarfVY Canis Majoris,Mu Cephei andVV Cephei A, three among thelargest known modern stars.
Once the black hole had formed at the protostar's core, it would continue to generate large amount ofradiant energy from 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.[6] Quasi-stars would have had a short maximum lifespan, approximately 7 million years,[7] during which the core black hole would have grown to about 1,000–10,000 solar masses (2×1033–2×1034 kg).[1][6] Theseintermediate-mass black holes have been suggested as the progenitors of modernsupermassive black holes such 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).[6] At these temperatures, each one would be about asluminous as a small galaxy.[1] 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).[6] This limiting temperature would mark the end of the quasi-star's life since there is nohydrostatic equilibrium at or below this limiting temperature.[6] The object would then quickly dissipate, leaving behind theintermediate mass black hole.[6]
