Iron star
In astronomy, the term iron star has been used for two unrelated types of star:
- a blue supergiant with a forest of forbidden FeII lines in its spectrum.
- a hypothetical type of compact star.
Blue supergiant
Compact iron star formation
An iron star is a hypothetical type of compact star that could occur in the universe in the extremely far future, after perhaps 101500 years.The premise behind the formation of iron stars states that muon-catalyzed fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into iron-56 nuclei, due to its nature as the atomic nucleus with the lowest mass per nucleon. 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 may be iron according to some predictions, it is distinct from an iron star.
By the end of 101026 to 101076 years, iron stars would have collapsed into neutron stars and black holes.
In popular culture
- The Soviet film The Andromeda Nebula 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 written when steady state theory was dominant and iron stars were expected to exist in the Milky Way.
- The Wrath of the Gods submod for the game Terraria includes the Avatar of Emptiness— a God from a dead universe who uses an iron star as an attack by launching streams of molten iron from it at the player.