In astronomy, an iron star is a hypothetical type of compact star.
Unrelatedly, the term "iron star" is also used for blue supergiants which have a forest of forbidden FeII lines in their spectra. They are potentially quiescent hot luminous blue variables. Eta Carinae has been described as a prototypical example.
|Event type||Formation of a hypothetical type of compact star|
|Date||c. 101500 years from now|
|Duration||c. 101026 to 101076 years from now|
|Epoch||Extremely far future|
|Source||Fusion occurring via quantum tunnelling causing nuclei to fuse into iron-56 nuclei|
|Notable features||Only a possibility if protons do not decay.|
|Followed by||Formation of neutron stars and black holes|
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 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. 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.