Iron planet

Comparison of sizes of planets with different compositions

An iron planet is a type of planet that consists primarily of an iron-rich core with little or no mantle. Mercury is the largest celestial body of this type^{[citation needed]} in the Solar System, but larger iron-rich exoplanets may exist. Also known as a Cannonball.^[1]

Origin

Iron-rich planets may be the remnants of normal metal/silicate rocky planets whose rocky mantles were stripped away by giant impacts. Some are believed to consist of diamond fields. Current planet formation models predict iron-rich planets will form in close-in orbits or orbiting massive stars where the protoplanetary disk presumably consists of iron-rich material.^[2]

Characteristics

Iron-rich planets are smaller and more dense than other types of planets of comparable mass.^[3] Such planets would have no plate tectonics or strong magnetic field as they cool rapidly after formation.^[2]

Candidates

Some extrasolar planet candidates that may be composed mainly of iron are KOI-1843 b,^[4] Kepler-70b and Kepler-10b.

See also

• Dwarf planet
• Extrasolar planet
• Terrestrial planet

References

v t e Exoplanetology Types Terrestrial Carbon planet Coreless planet Desert planet Ice planet Iron planet Lava planet Ocean planet Sub-Earth Super-Earth Gas giant Carbon giant Chthonian planet Eccentric Jupiter Helium planet Hot Jupiter Hot Neptune Ice giant Mini-Neptune Puffy planet Super-Jupiter Other types Solid giant Brown dwarf Circumbinary planet Double planet Mesoplanet Planetar Protoplanet Pulsar planet Sub-brown dwarf Systems Binary star Exocomet Exomoon Exoplanet Extragalactic planet Interstellar comet Planetary system Rogue planet Trojan planet Retrograde planet Mean-motion resonances Titius–Bode laws Planets orbiting red dwarfs Planets orbiting white dwarfs Planets orbiting brown dwarfs Planets in globular clusters Detection Direct imaging list Microlensing list Pulsar timing list Radial velocity list Transit method list Transit-timing variation Astrometry Polarimetry Habitability Circumstellar habitable zone Earth analog Earth Similarity Index Extraterrestrial liquid water Goldilocks planet Potentially habitable exoplanets Catalogues NASA Exoplanet Archive Exoplanet Data Explorer Extrasolar Planets Encyclopaedia Catalog of Nearby Habitable Systems NASA Star and Exoplanet Database Lists Exoplanetary host stars Exoplanet extremes Exoplanet firsts Kepler Multiplanetary systems Stars with proplyds Terrestrial candidates Unconfirmed exoplanets Other Exoplanet phase curves Exoplanet skies Sudarsky exoplanet classification Discoveries of exoplanets Search projects