Quasi-star

A quasi-star (also called black hole star) is a hypothetical type of extremely massive star that may have existed very early in the history of the Universe. Unlike modern stars, which are powered by nuclear fusion in their cores, a quasi-star's energy would come from material falling into a central black hole.^[1]

Size comparison of a quasi-star compared to several known giant stars. Even the largest known star, UY Scuti, is severely dwarfed.

A quasi-star is predicted to have formed when the core of a large protostar collapses into a black hole during its formation and the outer layers of the star are massive enough to absorb the resulting burst of energy without being blown away (as they are with modern supernovae). Such a star would have to be at least 1,000 solar masses (2.0×10³³ kg).^[1] Stars this large could only form early in the history of the Universe before the hydrogen and helium were contaminated by heavier elements; see Population III stars.

Once the black hole had formed at the core of the protostar, it would continue generating a large amount of radiant energy from the infall of additional stellar material. This energy would counteract the force of the gravity, creating an equilibrium similar to the one that supports modern fusion-based stars.^[2] A quasi-star is predicted to have had a maximum lifespan of about 7 million years,^[3] after which the core black hole would have grown to about 1,000–10,000 solar masses (2×10³³–2×10³⁴ kg).^[1][2] These intermediate-mass black holes have been suggested as the origin of the modern era's supermassive black holes. Quasi-stars are predicted to have surface temperatures limited to about 4,000 K (3,730 °C),^[2] but, with diameters of approximately 10 billion kilometres (66.85 au) or 7,187 times that of the Sun, each one would produce as much light as a small galaxy.^[1]

See also

• Quasar

References

Star
Evolution	Formation Pre-main-sequence star Main sequence Red giant branch Horizontal branch Asymptotic giant branch Dredge-up Instability strip Red clump PG1159 star Mira variable Planetary nebula Protoplanetary nebula Luminous red nova Luminous blue variable Wolf–Rayet star Stellar population Supernova Supernova impostor Hypernova Hertzsprung–Russell diagram Color–color diagram
Protostars	Molecular cloud H II region Bok globule Young stellar object Herbig–Haro object Hayashi track Henyey track Orion T Tauri FU Orionis Herbig Ae/Be
Luminosity class	Subdwarf Dwarf Blue Red White Yellow Black Brown Subgiant Giant Blue Red Bright giant Supergiant Blue Red Yellow Hypergiant Yellow Blue straggler Variable star
Spectral classification	O B A F G K M Be OB Subdwarf O Subdwarf B Late-type Chemically peculiar Am Ap/Bp Oscillating Barium Carbon CH CN Extreme helium Lambda Boötis Lead Mercury-manganese S Shell Technetium
Remnants	White dwarf Black dwarf Helium planet Neutron star Pulsar Binary X-ray X-ray binary X-ray burster Magnetar Stellar black hole Compact star Quark Strange Preon Planck Exotic Stellar core: EF Eridani B
Theoretical stars	Dark-matter star Dark-energy star Black star Gravastar Frozen star Q star Quasi-star Thorne–Żytkow object Iron star Blitzar
Nucleosynthesis	Deuterium burning Lithium burning Proton–proton chain CNO cycle Helium flash Triple-alpha process Carbon burning Neon burning Oxygen burning Alpha process Silicon burning S-process R-process Fusor Nova Remnants
Structure	Core Convection zone Microturbulence Oscillations Radiation zone Atmosphere Photosphere Starspot Chromosphere Corona Stellar wind Bubble Asteroseismology Eddington luminosity Kelvin–Helmholtz mechanism
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Star systems	Binary Contact Common envelope Multiple Accretion disk Star cluster Open cluster Globular cluster Super star cluster Planetary system Earth's Solar System
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Related articles	Substellar object Brown dwarf Sub-brown dwarf Planet Galactic year Galaxy Supercluster Helioseismology Guest star Constellation Asterism Gravity Intergalactic star Infrared dark cloud Starfield
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