Team identifies auroras outside our solar system

Posted by Ken Kola

University of Leicester planetary scientists believe they've found the first clear evidence that auroras occur outside our solar system.

Auroras occur when charged particles in an object’s magnetosphere collide with atoms in its upper atmosphere, making them glow.  However, before hitting the atmosphere, these particles also emit radio waves into space.

Auroras have been spotted on several planets within our solar system: indeed, the brightest, on Jupiter, are 100 times brighter than those on Earth. And now a new study has shown that processes very similar to those which power Jupiter’s auroras could be responsible for radio emissions detected from a number of objects outside our solar system.

And - very usefully - the radio emissions are powerful enough to be detectable across interstellar distances, meaning that auroras could provide an effective way of observing new objects outside our solar system.

The study shows that the radio emissions from a number of ultracool dwarfs may be caused in a very similar, but significantly more powerful, way to Jupiter’s auroras.

"We have recently shown that beefed-up versions of the auroral processes on Jupiter are able to account for the radio emissions observed from certain 'ultracool dwarfs' - bodies which comprise the very lowest mass stars - and 'brown dwarfs' - 'failed stars' which lie in between planets and stars in terms of mass," says Leicester's Dr Jonathan Nichols.

"These results strongly suggest that auroras do occur on bodies outside our solar system, and the auroral radio emissions are powerful enough  - one hundred thousand times brighter than Jupiter's - to be detectable across interstellar distances."

The findings could have major implications for the detection of planets and objects outside our solar system which can't be discovered with other methods.

What’s more, the radio emission could provide key information about the length of the planet’s day, the strength of its magnetic field, how the planet interacts with its parent star and even whether it has any moons.

"I am part of a group who have recently been awarded time on the Low Frequency Array (LOFAR) - centred in the Netherlands but with stations across a number of countries in northern Europe including the UK -  to try to observe auroras on exoplanets, so hopefully there will be some interesting results soon," says Nichols.