Silicate precursor silane detected in cold low-metallicity brown dwarf.

Within 20 pc of the Sun, there are currently 29 known cold brown dwarfs-sources with measured distances and an estimated effective temperature between that of Jupiter (170 K) and approximately 500 K (ref. ). These sources are almost all isolated and are the closest laboratories we have for detailed atmospheric studies of giant planets formed outside the Solar System.

Methane emission from a cool brown dwarf.

Beyond our Solar System, aurorae have been inferred from radio observations of isolated brown dwarfs. Within our Solar System, giant planets have auroral emission with signatures across the electromagnetic spectrum including infrared emission of H and methane. Isolated brown dwarfs with auroral signatures in the radio have been searched for corresponding infrared features, but only null detections have been reported.