Brown drawfs are failed stars. They fill the gap between giant gas planets, such as Jupiter and Saturn, and faint cool stars. They do n’t contain enough mass to initiate nuclear fusion in their cores, so they only glow feebly at infrared wavelengths. The first confirmed brown dwarf was found twenty years ago and only a few hundred of these elusive objects are known. The closest brown dwarfs to the Solar System form a pair called Luhman 16AB about 6.6 light-years from Earth in the southern constellation of Vela (The Sail). This pair is the third closest star system to the Earth, after Alpha Centauri and Barnard’s Star. The fainter brown dwarf Luhman 16B changes slightly in brightness every few hours as it rotates—a clue that it might have surface features.
It turns out that the markings are clouds of silicate rock and iron particles kept aloft by turbulence in the atmosphere. It snows iron on Luhman 16B.
The images above are from IR data of Luhman 16B gathered using the ESO’s Very Large Telescope.
Image Credit: ESO