A team of astronomers has discovered the most powerful aurora ever observed. But unlike our own Northern Lights, this astronomical phenomenon can be found 18 light years away in the skies above the brown dwarf LSR J1835+3259.
The international team of stargazers observed the distant aurora using the National Radio Astronomy Observatory in New Mexico and the Hale telescope in San Diego. They found a series of colourful green and yellow streaks above the star, a result of oxygen and sodium ions being hit by electrons in its atmosphere. There are also red emissions produced by similar collisions with hydrogen, though the resulting light is actually too red for humans to see. But what could be seen would be incredible: the scientists report that the aurora would appear 1,000,000 times brighter than our own Northern Lights. The results are published in Nature, and the above image is an artist's interpretation.
Interestingly, the result also solves a problem that's bugged some astronomers for years. In the past, brown dwarves — which are huge balls of hot gas that are kind of part-planet, part-star — have been seen to dim and brighten periodically. The new observation also comes and goes, as the astronomical body rotates on its axis every 2 hours. The team reckon that aurora on other brown dwarves could account for the varying brightness. The observation also hints that we should think a little differently about brown dwarves generally. "They have cool atmospheres with clouds, just like Jupiter, and now we see they have auroras, too," Stuart Littlefair told the Guardian. "It's more evidence we should think of them as scaled-up planets more than scaled-down stars."
Sadly, even though the aurora is so bright, you won't be seeing it for yourself any time soon: even at full brightness, the brown dwarf is reported to be 150,000 times too dim to be observed by the human eye.
Image by Chuck Carter and Gregg Hallinan/Caltech