Planetary mass object
A Planetary mass object, PMO, or planemo is a celestial object with a mass that falls within the range of the definition of a planet - i.e. a mass greater than that of a minor object, yet smaller than that of a nuclear reactive brown dwarf or star. By definition all planets are planetary mass objects but the purpose of the term is to describe objects which do not conform to typical expectations for a planet, such as free floating planets not orbiting a star, or objects which have formed through cloud-collapse rather than accretion which are sometimes called sub-brown dwarfs.
Recent discoveries
Cha 110913-773444 was discovered by the Spitzer Space Telescope. It is 8 times more massive than Jupiter, and an estimated 2 million years old. It is encircled by a disk of dust. It is 500 light-years away from Earth.
The first Planemos discovered outside the Solar System were those orbiting PSR 1257+12, discovered in 1992 by Aleksander Wolszczan and Dale Frail;[1] as pulsar planets, they surprised many astronomers who expected to find planets only around main sequence stars.
References
External links
- Gibor Basri, Michael E. Brown, Planetesimals to Brown Dwarfs: What is a Planet?, 2006 Preprint
- Defining "Planet" by Gibor Basri
- BBC News: Strange 'twin' new worlds found
- ScienceDaily: New Study Suggests 'Planemos' May Spawn Planets And Moons June 6, 2006 (University of Toronto)
Celestial objects with Planet related terminology
Terms containing and related to the modern astronomical term 'planet', that are also a term for a type of celestial object.
- Double planet
- Dwarf planet
- Exoplanet - celestial body outside that solar system
- Mesoplanet
- Minor planet – celestial body smaller than a planet
- protoplanet
- Planemo
- planetesimal
- Planetoid
- Planetar (astronomy)
- Pulsar planet
See also
