Hypothetical early-universe star with a black hole core
"Black hole star" redirects here. For black holes created from stars, see
Stellar black hole. For stars that become black holes, see
Supernova. For stars with black hole cores, see
Hawking star. For types of stars denser than neutron stars, see
Exotic star. For the 1994 Soundgarden song, see
Black Hole Sun.
Not to be confused with a quasi-stellar object or
quasar.
A quasi-star (also called black hole star) is a
hypothetical type of extremely
massive and
luminousstar that may have existed early in the
history of the Universe. They are thought to live around 7-10 million years. Unlike modern stars, which are powered by
nuclear fusion in their cores, a quasi-star's
energy would come from material falling into a
black hole at its core.
Quasars emit massive amounts of
energy across the
electromagnetic spectrum, from
radio waves to
gamma rays. They were first proposed in the 1960s and have since provided valuable insights into the early
universe, galaxy formation, and the behavior of
black holes. Although they have not been observed, they are considered to be the largest possible
stars in the
universe.[1]
Formation and properties
A quasi-star would have resulted from the core of a large
protostar collapsing into a
black 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 modern
supernovae. Such a star would have to be at least 1,000
solar masses (2.0×1033 kg).[2] Quasi-stars may have also formed from
dark matter halos drawing in enormous amounts of gas via gravity, which can produce
supermassive 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 massive
Population III stars.[5] Such stars would dwarf
VY Canis Majoris,
UY Scuti, and
Stephenson 2 DFK 1 also known as
Stephenson 2-18, three among the
largest known modern stars.
Once the black hole had formed at the protostar's core, it would continue generating a large amount of
radiant energy from the infall of stellar material. This constant outburst of energy would counteract the force of
gravity, 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] These
intermediate-mass black holes have been suggested as the progenitors of modern
supermassive black holes such as
the 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 as
luminous 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 no
hydrostatic equilibrium at or below this limiting temperature.[6] The object would then quickly dissipate, leaving behind the
intermediate mass black hole.[6]
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
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.