Auroras Make 'Failed Stars' Brown Dwarfs More Planet Like

Brown dwarfs, often called failed stars, may be more planet-like than earlier thought.

A new study published in the journal Nature, details spotting of auroras on a brown dwarf about 20 light years away. Auroras are characteristic of planets with magnetic activity.

"We're finding that brown dwarfs are not like small stars in terms of their magnetic activity; they're like giant planets with hugely powerful auroras. If you were able to stand on the surface of the brown dwarf we observed-something you could never do because of its extremely hot temperatures and crushing surface gravity-you would sometimes be treated to a fantastic light show courtesy of auroras hundreds of thousands of times more powerful than any detected in our solar system," said Caltech Assistant Professor Gregg Hallinan who led the study.

Unlike planets like Earth which produce auroras, also called northern and southern lights, when stellar winds drive charged particles along Earth's magnetic lines, the mechanism of how charged particles could be producing the bright lights, are not completely known. However the auroras observed on the brown dwarf are much brighter than those planets witness.

The team also observed that the brown dwarf pulses radio waves much like planets and hypothesized that auroras could be causing the waves.

"We see a similar pulsing phenomenon from planets in our solar system and that radio emission is actually due to auroras," Hallinan said.