Brown-dwarf desert

The brown-dwarf desert is a theorized range of orbits around a star within which brown dwarfs are unlikely to be found as companion objects.

The paucity of brown dwarfs in close orbits was first noted between 1998 and 2000 when a sufficient number of extrasolar planets had been found to perform statistical studies.

[2] Subsequent studies have shown that brown dwarfs orbiting within 3–5 AU are found around less than 1% of stars with a mass similar to the Sun (M☉).

[6] This effect might be somewhat mitigated by the fact that objects of 3–5 MJ and above might excite eccentric perturbations in the disk, allowing for non-negligible mass accretion even in the presence of a gap.

[7] Objects that form further outside (a>80 AU), where the disk is prone to gravitational instabilities, might be able to reach the masses required to cross the planet–brown dwarf threshold.