Brown dwarfs are substellar objects not massive enough to sustain hydrogen-1 fusion reactions in their cores, unlike main-sequence stars. Brown dwarfs occupy the mass range between the heaviest gas giants and the lightest stars, with an upper limit around 75 to 80 Jupiter masses.
Brown dwarfs are heavy enough to fuse deuterium or lithium as well. Stars are categorized by spectral class, with brown dwarfs being 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. Habitability for hypothetical planets or moons orbiting brown dwarfs has been studied.
Computer models suggesting conditions for these bodies to have habitable planets are very stringent, the habitable zone being narrow and decreasing with time, due to the cooling of the brown dwarf.
The orbits there would have to be of very low eccentricity (of the order of 10−6) to avoid strong tidal forces that would trigger a greenhouse effect on the planets, rendering them uninhabitable.
It is not possible to land on a Brown Dwarf. There is no solid surface, it radiates immense heat and has a strong gravitation.
History of the Future
There are habitables planets possible at Brown Dwarfs.