Planet#Planetary-mass objects
Object of planetary mass (English planetary -mass object, PMO short ) is a collective term for astronomical objects with a mass that falls within the scope of the definition for planets of the solar system. Thus, the lower size limit is usually defined by the achievement of the hydrostatic equilibrium and the upper limit by a mass of about 13 Jupiter masses, which requires a minimal object for the deuterium fusion. However, the term is usually not used for the planets of the solar system, or exoplanets for, but for objects that are not gravitationally bound to a larger body ( not, for example orbiting a star ). The discovery of such objects, the clear definition of the term "planet" for additional problems. It has been enforced no universally accepted definition and no common term for these objects in the research. Among others, the names of stray planet or cosmic vagabond and (English) free floating planet, rogue planet, Planemo be used (of planetary mass object), planetar (formed planet and star) or orphan planet. Objects that are created by the gravitational collapse of a cloud, are sometimes called sub - brown dwarfs.
Free-flying planets are optically relatively hard to find. With infrared telescopes, however, some candidates for such objects in the Galaxy were due to their own heat signature is detected, so that we assume today that in our galaxy almost twice as many free-flying planets as stars exist.
Exemplary objects of planetary mass
Known examples of planetary mass objects are Cha 110913-773444, PSO J318.5 -22, S Ori 68 and S Ori 70 The latter sparked by his discovery and unclear classification as a star or planet from a debate from which the name " Planemo " emerged.
Cha 110913-773444 is surrounded by a disk of dust and was discovered with the Spitzer Space Telescope. Luhman had been discovered in 2004 in the discovery of Cha 110913-773444 then the smallest known brown dwarf, which is also surrounded by a protoplanetary disk of dust. This object - OTS 44 - has fifteen times Jupiter's mass, and can therefore be categorized as just a brown dwarf. However, Cha 110913-773444, with about 8 Jupiter masses only about half of the mass of OTS 44
The object PSO J318.5 -22, the discovery of which was published on October 1, 2013, according to present knowledge, has a mass of about six times Jupiter's mass and is therefore too small to be a star. He is the erdnächste, previously discovered celestial body of this kind
List of candidates (selection)
The following list contains some objects of planetary mass candidates that are not gravitationally bound to a more massive body.