Astrophysicists Detect Mysterious Radio Emissions Emanating From Brown Dwarf Stars

Clues indicate “failed stars” generate Auroral displays a million times more powerful than on Earth 

This artist's concept shows an auroral display on a brown dwarf. If you could see an aurora on a brown dwarf, it would be a million times brighter than an aurora on Earth. Credits: Chuck Carter and Gregg Hallinan/Caltech
This artist’s concept shows an auroral display on a brown dwarf. If you could see an aurora on a brown dwarf, it would be a million times brighter than an aurora on Earth.
Credits: Chuck Carter and Gregg Hallinan/Caltech

Space news (August 16, 2015) – 18.6 light-years from Earth

Called “failed stars” because they don’t have enough mass to fuse hydrogen in their cores and being too big to be classified as planets, brown dwarfs have been a focus of study for astrophysicists because their atmospheres’ are thought to be very similar to conditions on many of the exoplanets we have discovered.

Studying the atmosphere of cool brown dwarfs is easier than trying to gather data on the atmosphere of an exoplanet. Light from the parent star interferes with the readings taken of the atmosphere of an exoplanet, making it harder to view through all the glare.

“It’s challenging to study the atmosphere of an exoplanet because there’s often a much brighter star nearby, whose light muddles observations. But we can look at the atmosphere of a brown dwarf without this difficulty,” Greg Hallinan said.

Astrophysicists studying brown dwarfs since the early 2000s using a trio of observatories have detected brilliant auroras dancing across the atmosphere of brown dwarf LSRJ1835+3259. Vivid red auroras, due to the higher hydrogen content of its atmosphere, estimated to be a million times more energetic than any viewed on Earth. 

This is a whole new manifestation of magnetic activity for that kind of object,” said Leon Harding, a technologist at NASA’s Jet Propulsion Laboratory, Pasadena, California, and co-author of the study.

Auroras viewed on Earth are produced when charged particles, mostly electrons, from the solar wind strike atoms of oxygen and nitrogen in the atmosphere above the poles, resulting in vivid displays of mostly green colors that dance across the sky.

As the electrons spiral down toward the atmosphere, they produce radio emissions, and then when they hit the atmosphere, they excite hydrogen in a process that occurs on Earth and other planets,” said Gregg Hallinan, assistant professor of astronomy at the California Institute of Technology in Pasadena, who led the team. “We now know that this kind of auroral behavior is extending all the way from planets up to brown dwarfs.

What’s next?

Astrophysicists will now continue their studies of brown dwarfs using the Astronomy Observatory Very Large Array in New Mexico, the W.M. Keck Observatory in Hawaii, and the Hale Telescope at the Palomar Observatory in California. Plans to map the auroras of LSRJ1835+3259 are being discussed to see if they can find the source of the solar winds generating them. Brown dwarfs don’t generate a solar wind like other stars, so they’re kind of at a loss at this point as to the source. 

My vote is for an orbiting exoplanet moving through the magnetosphere of LSRJ1835+3259 generating a current producing spectacular, vivid red auroras that light up the atmosphere. A show one of our robot explorers may view up close one day, but for now, astrophysicists will have to settle for studying it from a distance.

At the very least, studying brown dwarfs will help astrophysicists understand the atmospheres’ of exoplanets viewed during the human journey to the beginning of space and time, better. 

Hallinan and the rest of the team are also hoping to take a close look at the magnetic fields of exoplanets in the future. The Owens Valley Long Wavelength Array is coming online and plans are to take a few measurements of candidates in the Exoplanet Zoo.

You can learn more about NASA’s mission to the stars here.

You can discover the Owens Valley Long Wavelength Array here.

Take a look at all the discoveries of the National Radio Astronomy Observatory here.

Discover the W.M. Keck Observatory here.

Learn more about the mission of the Palomar Observatory here.

Learn about the way galaxies merge to become one.

Read about the discovery of the first nearly Earth-sized exoplanet.

Learn about the discovery of geysers on the southern polar region of Enceladus erupting icy grains of water and organic materials into the E ring of Saturn.

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