NASA's Webb finds signs of possible aurorae on isolated brown dwarf

Astronomers have found a brown dwarf (an object more massive than Jupiter but smaller than a star) with infrared emission from methane, likely due to energy in its upper atmosphere. This is an unexpected discovery because the brown dwarf, W1935, is cold and lacks a host star; therefore, there is no obvious source for the upper atmosphere energy. The team speculates that the methane emission may be due to processes generating aurorae.

https://www.sciencedaily.com/releases/2024/01/240109170515.htm