page_title: Brown dwarf
section_title: Sub-brown dwarf
hierarchical_section_title: Brown dwarf / Theory / Low-mass brown dwarfs versus high-mass planets / Sub-brown dwarf
caption_attribution_description: Comparison of the Sol (Sun), Brown Dwarf Cha 110913-773444 and Jupiter
context_page_description: A brown dwarf is a type of substellar object that has a mass between those of the heaviest gas giant planets and the least massive stars, i.e. about 13 to 75–80 times that of Jupiter, or about 2.5×10²⁸ kg to 1.5×10²⁹ kg. Below this range are the sub-brown dwarfs, and above it are the red dwarfs. Brown dwarfs may be fully convective, with no layers or chemical differentiation by depth.
  Unlike the stars in the main sequence, brown dwarfs are not massive enough to sustain nuclear fusion of ordinary hydrogen to helium in their cores. They are, however, thought to fuse deuterium. If their mass is > 65 MJ they may also fuse lithium. It is also debated whether brown dwarfs would be better defined by their formation processes rather than by their nuclear fusion reactions.
  Stars are categorized by spectral class, with brown dwarfs designated as types M, L, T, and Y. Despite their name, brown dwarfs are of different colors. Many brown dwarfs would likely appear magenta to the human eye, or possibly orange/red. Brown dwarfs are not very luminous at visible wavelengths.
  There are planets known to orbit brown dwarfs, such as 2M1207b, MOA-2007-BLG-192Lb, and 2MASS J044144b.
context_section_description: Objects below 13 MJ, called sub-brown dwarf or planetary-mass brown dwarf, form in the same manner as stars and brown dwarfs (i.e. through the collapse of a gas cloud) but have a mass below the limiting mass for thermonuclear fusion of deuterium.
  Some researchers call them free-floating planets, whereas others call them planetary-mass brown dwarfs.
caption: A size comparison between the Sun, a young sub-brown dwarf, and Jupiter. As the sub-brown dwarf ages, it will gradually cool and shrink
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