Iron star

In astronomy, 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 iron stars states that cold fusion occurring via quantum tunnelling would cause the light nuclei in ordinary matter to fuse into iron-56 nuclei. Fission and alpha-particle emission would then make heavy nuclei decay into iron, converting stellar-mass objects to cold spheres of iron.^[1] The formation of these stars is only a possibility if the proton does not decay. Though the surface of a neutron star may be iron, according to some predictions, it is distinct from an iron star.

Unrelatedly, the term is also used for blue supergiants which have a forest of forbidden Fe_II lines in their spectra. They are potentially quiescent hot luminous blue variables. Eta Carinae has been described as a prototypical example.^[2][3]

In popular culture

• The Soviet film The Andromeda Nebula is about a starship low on fuel caught by the gravity of an iron star, which could only be seen in the infrared. It is based on the novel Andromeda: A Space-Age Tale by Ivan Yefremov written when Steady State theory was dominant and iron stars were expected to exist in the Milky Way.

See also

• Future of an expanding universe
• Hypothetical star
• Heat death of the universe

References