Hypothetical star
Encyclopedia
A hypothetical star is a type of star that is speculated to exist but has yet to be definitively observed. Scientifically speculated hypothetical stars include:
Specific hypothetical stars include:
- Black dwarfBlack dwarfA black dwarf is a hypothetical stellar remnant, created when a white dwarf becomes sufficiently cool to no longer emit significant heat or light...
, the final state for a star, like the SunSunThe Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
, that is too small to become either a black hole or a neutron star. It would take a star like our Sun roughly a quadrillion years to reach this state, so none are believed to exist today. - Black starBlack Star (semiclassical gravity)A black star is a gravitational object composed of matter. It is a theoretical alternative to the black hole concept from general relativity. The theoretical construct was created through the use of semiclassical gravity theory...
, a star predicted in semiclassical gravitySemiclassical gravitySemiclassical gravity is the approximation to the theory of quantum gravity in which one treats matter fields as being quantum and the gravitational field as being classical....
which collapses into a black hole state but has neither a gravitational singularityGravitational singularityA gravitational singularity or spacetime singularity is a location where the quantities that are used to measure the gravitational field become infinite in a way that does not depend on the coordinate system...
nor an event horizonEvent horizonIn general relativity, an event horizon is a boundary in spacetime beyond which events cannot affect an outside observer. In layman's terms it is defined as "the point of no return" i.e. the point at which the gravitational pull becomes so great as to make escape impossible. The most common case...
. - Boson star, a star made of bosons, such as photonPhotonIn physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...
s or gluonGluonGluons are elementary particles which act as the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles....
s, rather than conventional matter - Dark energy starDark energy starA dark-energy star is a hypothetical compact astrophysical object, which a minority of physicists feel might constitute an alternative explanation for observations of astronomical black hole candidates. Dark energy is invisible to the human eye; however, it can be tracked with difficulty by...
, a conjectured alternative to a black holeBlack holeA black hole is a region of spacetime from which nothing, not even light, can escape. The theory of general relativity predicts that a sufficiently compact mass will deform spacetime to form a black hole. Around a black hole there is a mathematically defined surface called an event horizon that... - Fuzzball: a formulation of black holes in string theoryString theoryString theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...
- GravastarGravastarA gravastar is an object hypothesized in astrophysics as an alternative to the black hole theory by Pawel Mazur and Emil Mottola. It results from assuming real, physical limitations on the formation of black holes...
, an alternative to a black hole that denies the possibility of a singularity - Intermediate mass black hole: a black hole that is roughly a few thousand times the mass of the Sun; thus larger than a stellar mass black hole yet smaller than a supermassive black holeSupermassive black holeA supermassive black hole is the largest type of black hole in a galaxy, in the order of hundreds of thousands to billions of solar masses. Most, and possibly all galaxies, including the Milky Way, are believed to contain supermassive black holes at their centers.Supermassive black holes have...
- Iron starIron starIn astronomy, an iron star is a hypothetical type of star that could occur in the universe in 101500 years. The premise behind iron stars states that cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into iron-56 nuclei...
, a final state for a star in the far future of the universe, when all matter is transmuted to iron via quantum tunnellingQuantum tunnellingQuantum tunnelling refers to the quantum mechanical phenomenon where a particle tunnels through a barrier that it classically could not surmount. This plays an essential role in several physical phenomena, such as the nuclear fusion that occurs in main sequence stars like the sun, and has important... - Magnetospheric eternally collapsing objectMagnetospheric eternally collapsing objectMagnetospheric Eternally Collapsing Objects or MECOs are proposed alternatives to black holes advocated by Darryl Leiter and Stanley Robertson. They are a variant of eternally collapsing objects or ECOs proposed by Abhas Mitra in 1998. Mitra had devised an ostensive proof that black holes cannot...
: a hypothetical alternative to black holes - Population III star: stars virtually free of metalsMetallicityIn astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...
believed to have existed in the early universe. - Q star, a type of heavy neutron star
- Quark starQuark starA quark star or strange star is a hypothetical type of exotic star composed of quark matter, or strange matter. These are ultra-dense phases of degenerate matter theorized to form inside particularly massive neutron stars....
, a star composed of strange matterStrange matterStrange matter is a particular form of quark matter, usually thought of as a "liquid" of up, down, and strange quarks. It is to be contrasted with nuclear matter, which is a liquid of neutrons and protons , and with non-strange quark matter, which is a quark liquid containing only up and down quarks... - QuasistarQuasistarA quasi-star is a hypothetical type of extremely massive star that may have existed very early in the history of the Universe...
, a star from the early universe with a black hole at its centre - White holeWhite holeA white hole, in general relativity, is a hypothetical region of spacetime which cannot be entered from the outside, but from which matter and light may escape. In this sense it is the reverse of a black hole, which can be entered from the outside, but from which nothing, including light, may escape...
, the polar opposite of a black hole, it ejects matter from its core into space.
Specific hypothetical stars include:
- Nemesis (star)Nemesis (star)Nemesis is a hypothetical hard-to-detect red dwarf star, white dwarf star or brown dwarf, originally postulated in 1984 to be orbiting the Sun at a distance of about 95,000 AU , somewhat beyond the Oort cloud, to explain a perceived cycle of mass extinctions in the geological record, which seem to...
, a star proposed as a companion to the Sun by Richard A. MullerRichard A. MullerRichard A. Muller is a noted American professor of physics at the University of California, Berkeley. He is also a faculty senior scientist at the Lawrence Berkeley National Laboratory.-Career:...
in 1984 - 3 Cassiopeiae3 Cassiopeiae3 Cassiopeiae is a hypothetical star catalogued by English astronomer John Flamsteed. It bears no identity with actual stars observed today. Unlike 34 Tauri, which was the planet Uranus, 3 Cas was not reconciled by later knowledge....
, a star recorded by astronomer John FlamsteedJohn FlamsteedSir John Flamsteed FRS was an English astronomer and the first Astronomer Royal. He catalogued over 3000 stars.- Life :Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed...
, but never seen again - 34 Tauri, a star recorded by John FlamsteedJohn FlamsteedSir John Flamsteed FRS was an English astronomer and the first Astronomer Royal. He catalogued over 3000 stars.- Life :Flamsteed was born in Denby, Derbyshire, England, the only son of Stephen Flamsteed...
later revealed to have been the planet UranusUranusUranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus , the father of Cronus and grandfather of Zeus...