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Outer space aurora puts Northern Lights to shame

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An artist conception of an aurora over the polar region of a brown dwarf. Chuck Carter and Gregg Hallinan, Caltech

Astronomers for the first time have discovered an aurora - similar but much brighter than the famed Northern Lights - outside our solar system.

Emanating from what is believed to be a brown dwarf called LSR J1835+3259, this aurora is more than 18 light years away and 10,000 times more powerful than any one ever seen.

While it can't be seen with the naked eye, scientists believe it would appear bright red - in contrast to the dancing green, purple or blue light seen on Earth and produced by the interaction between sun's solar winds and our planet's magnetic field.

"What we see on this object appears to be the same phenomenon we've seen on Jupiter, for example, but thousands of times more powerful," Caltech's Gregg Hallinan, who was part of an international team that discovered the aurora and co-authored a study on the discovery that appears Wednesday in Nature.

"The atmosphere is largely made up of hydrogen so the aurora we see in this brown dwarf is not glowing green like the Earth's aurora but rather red like what we see from Jupiter and Saturn," he told CBS News. "It's caused by the interaction of the same kind of particles but with a hydrogen atmosphere rather than an oxygen-rich atmosphere."

Eight years ago, Hallinan discovered pulsing radio waves on a brown dwarf, which is something "we know happens when they have an aurora."

That set off a long-running chase, with Hallinan and his team spotting LSR J1835+3259, using the Karl G. Jansky Very Large Array at radio wavelengths, along with the 5-meter Hale Telescope on Palomar Mountain and the 10-meter Keck Telescope in Hawaii at optical wavelengths.

"We finally made the critical measurement in 2012 that confirms these are actually aurora," Hallinan said, adding that they can't say for sure what it looks like but do know its color.

"We used a spectrometer to analyze optical lights from the brown dwarf and we saw there were hydrogen lines there associated with a hydrogen atmosphere," he said. "That is in the red part of the spectrum."

Hallinan said the discovery should provide a better understanding of brown dwarfs. Sometimes called failed stars of our galaxies, they are objects that fall in between a planet and a star - more massive than planets, yet too small to trigger the thermonuclear reactions at their cores that power stars.

The astronomers said their observations of LSR J1835+3259 indicate that the coolest stars and brown dwarfs have outer atmospheres that support auroral activity, rather than the type of magnetic activity seen on more-massive and hotter stars like the sun.

"The question is whether brown dwarfs would have a corona and flare like the sun does or whether they would have magnetic fields and aurora like the Earth and other planets have," Hallinan said. "It turns out they have aurora and magnetic field like the planets, so we know the transition from star-like activity to planet-like activity happens in the brown dwarf regime."

Time Lapse: The Great Solstice Aurora

The presence of an aurora could also be a crucial piece in the search for Earth-like exoplanets, two of which were only discovered last month. The planets known as HD 7924c and HD 7924d, are "super Earths" with masses about 7.9 and 6.4 times greater, respectively, than that of our home planets. The planets orbit the star HD 7924, which lies just 54 light-years from the sun.

"We now know we can detect this kind of aurora from brown dwarfs," Hallinan said.

"Now, the next step is trying to detect the kind of aurora from exo-solar planets, planets that are orbiting other stars and trying to understand whether they have magnetic fields and whether those magnetic fields are important to detecting life on those planets," he said. "Are those magnetic fields strong enough to shield them from X-ray flares and coronal mass ejection of their star?"

Don Hampton, of the Geophysical Institute at the University of Alaska Fairbanks and who didn't take part in the study, called the findings "quite exciting."

"Seeing auroral signature in a strongly magnetized object outside of our solar system is groundbreaking, but not too surprising," Hampton said. "Seeing this phenomenon at a stellar object is also groundbreaking, and maybe a bit more surprising. It will be interesting to hear how the modelers determine what is driving this aurora. At Earth it is the energy of the solar wind that drives the processes the lead to aurora. What is the energy source at the brown dwarf?"

Hampton agreed with Hallinan that the aurora could prove helpful in the search for alien life.

"This does lead to the conclusion that, with instruments sensitive enough, we may be able to see aurora on extra-solar planets," he said. "If these show signs of certain gases, specifically oxygen, nitrogen, maybe carbon-dioxide, this would be a strong indication of life outside of our solar system."

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