astronomy Astronomy () is a natural science that studies astronomical object, celestial objects and phenomena. It uses mathematics, physics, and chemistry in order to explain their origin and chronology of the Universe, evolution. Objects of interest ...

, an iron star is a hypothetical type of

compact star In astronomy, the term compact star (or compact object) refers collectively to white dwarfs, neutron stars, and black holes. It would grow to include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects ha ...

. Unrelatedly, the term "iron star" is also used for

blue supergiant A blue supergiant (BSG) is a hot, luminous star, often referred to as an OB supergiant. They have luminosity class I and spectral class B9 or earlier. Blue supergiants are found towards the top left of the Hertzsprung–Russell diagram, above ...

s which have a forest of forbidden Fe_II lines in their spectra. They are potentially quiescent hot

luminous blue variable Luminous blue variables (LBVs) are massive evolved stars that show unpredictable and sometimes dramatic variations in their spectra and brightness. They are also known as S Doradus variables after S Doradus, one of the brightest stars of the Larg ...

Eta Carinae Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in t ...

has been described as a prototypical example.

Formation

An iron star is a hypothetical type of

that could occur in the

universe The universe is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. The Big Bang theory is the prevailing cosmological description of the development of the universe. Acc ...

in the extremely far future, after perhaps 10¹⁵⁰⁰ years. The premise behind the formation of iron stars states that cold

fusion Fusion, or synthesis, is the process of combining two or more distinct entities into a new whole. Fusion may also refer to: Science and technology Physics *Nuclear fusion, multiple atomic nuclei combining to form one or more different atomic nucl ...

occurring via

quantum tunnelling Quantum tunnelling, also known as tunneling ( US) is a quantum mechanical phenomenon whereby a wavefunction can propagate through a potential barrier. The transmission through the barrier can be finite and depends exponentially on the barrier h ...

would cause the light nuclei in ordinary matter to fuse into

iron-56 Iron-56 (56Fe) is the most common isotope of iron. About 91.754% of all iron is iron-56. Of all nuclides, iron-56 has the lowest mass per nucleon. With 8.8 MeV binding energy per nucleon, iron-56 is one of the most tightly bound nuclei. N ...

nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting stellar-mass objects to cold spheres of iron. The formation of these stars is only a possibility if protons do not decay. Though the surface of a

neutron star A neutron star is the collapsed core of a massive supergiant star, which had a total mass of between 10 and 25 solar masses, possibly more if the star was especially metal-rich. Except for black holes and some hypothetical objects (e.g. white ...

may be iron according to some predictions, it is distinct from an iron star. By the end of 10^10²⁶ to 10^10⁷⁶ years, iron stars would have collapsed into neutron stars and

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

In popular culture

* The Soviet film ''

The Andromeda Nebula ''The Andromeda Nebula'' (russian: Туманность Андромеды) is a 1967 Soviet science fiction film starring Sergei Stolyarov and directed by Yevgeni Sherstobitov at the Dovzhenko Film Studios. The film was originally intended t ...

'' is about a starship low on fuel caught by an iron star's gravity, with the star itself being so dim that it can only be seen in the infrared. It is based on the novel '' Andromeda Nebula'' by

Ivan Yefremov Ivan Antonovich (real patronymic Antipovich) Yefremov ( ru , Ива́н Анто́нович (Анти́пович) Ефре́мов; April 23, 1908 – October 5, 1972; last name sometimes transliterated as Efremov) was a Soviet paleonto ...

written when

steady state theory In cosmology, the steady-state model, or steady state theory is an alternative to the Big Bang theory of evolution of the universe. In the steady-state model, the density of matter in the expanding universe remains unchanged due to a continuous ...

was dominant and iron stars were expected to exist in the Milky Way.

References

{{Portal bar, Astronomy, Spaceflight, Outer space, Solar System Star types Hypothetical stars

Star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

Ultimate fate of the universe

Formation

In popular culture

See also

References