A size comparison between our
Sun, a young sub-
brown dwarf, and
Jupiter. As the sub-brown dwarf ages, it will gradually cool and shrink.
Sub-brown dwarf is a planetary-mass object whose mass is smaller than the low-mass cut-off for brown dwarfs (around 13 times the mass of Jupiter). Unlike proper brown dwarfs, they are not massive enough to fuse deuterium. Sub-brown dwarfs are formed in the manner of stars, through the collapse of a gas cloud, and not through accretion or core collapse from a circumstellar disc. The distinction between a sub-brown dwarf and a planet is unclear; astronomers are divided into two camps as whether to consider the formation process of a planet as part of its division in classification.1
An alternate definition involves the same mass range (less than a brown dwarf, but in the planetary range), but is free of gravitational attachment with any star. These are generally referred to as free-floating planets. This usage is in the IAU Extrasolar Planets provisional definition of a planet.2
List of suspected sub-brown dwarfs
See also
References
