Magnetospherically driven optical and radio aurorae at the end of the stellar main sequence : Nature
Aurorae are detected from all the magnetized planets in our SolarSystem, including Earth. They are powered by magnetosphericcurrent systems that lead to the precipitation of energetic electronsinto the high-latitude regions of the upper atmosphere. In the caseof the gas-giant planets, these aurorae include highly polarizedradio emission at kilohertz and megahertz frequencies producedby the precipitating electrons, as well as continuum and line emis-sion in the infrared, optical, ultraviolet and X-ray parts of thespectrum, associated with the collisional excitation and heatingof the hydrogen-dominated atmosphere. Here we report sim-ultaneous radio and optical spectroscopic observations of an objectat the end of the stellar main sequence, located right at the bound-ary between stars and brown dwarfs, from which we have detectedradio and optical auroral emissions both powered by magneto-spheric currents.