The first auroras ever seen outside our solar system have been discovered by astronomers. The light shows are more powerful than any other auroras ever witnessed, perhaps 1 million times brighter than any on Earth, researchers said.
Auroras are the radiant displays of colors in the sky known on Earth as the northern or southern lights, are also seen on all of the other planets with magnetic fields in the solar system. They are caused by currents in the magnetosphere of a planet — the shell of electrically charged particles captured by a planet’s magnetic field — that force electrons to rain down on the atmosphere, colliding with the molecules within and making them give off light.
Astronomers investigated a mysterious Jupiter-size object called LSR J1835+3259, located about 18.5 light-years from Earth to see if Auroras existed outside of our solar system. The object is a few dozen times more massive than Jupiter, suggesting it is too heavy to be a planet but too light to be a star, the researchers said.
They found the LSR J1835+3259 was likely a brown dwarf, usually known as a failed star. Brown dwarfs were discovered to emit radio waves. “That was very surprising,” said Gregg Hallinan, an astronomer at the California Institute of Technology in Pasadena and lead author of the new study. “Typically, we see radio waves from really active stars, not objects with much cooler temperatures like brown dwarfs,” he told Space.com.
Hallinan later found that LSR J1835+3259 emitted radio waves in pulses. “We knew that radio pulses from planets in our own solar system were caused by aurorae, so we thought maybe brown dwarfs had aurorae too,” he said.
The researchers were then able to detect sings of auroras on LSR J1835+3259 by using the Karl G. Jansky Very Large Array in New Mexico to scan radio wavelengths of light, along with the Hale Telescope on Palomar Mountain in California and the W. M. Keck Observatory in Hawaii to scan visible wavelengths of light.
“If you were to somehow stand on the brown dwarf’s surface and survive — the surface gravity is maybe 100 times more intense than Earth’s, and the temperature is several hundred to several thousand degrees — you’d see a beautiful bright-red aurora,” Hallinan said. “The colors of auroras depend on whatever the atmosphere they take place in is made of. In Earth’s case, it’s mostly green and blue and red because of oxygen and nitrogen. When it comes to Jupiter, Saturn and brown dwarfs — which have hydrogen-rich atmospheres — you’d see red, and there would be ultraviolet and infrared wavelengths as well.”
It was thought Jupiter had the brightest auroras. these newfound auroras are more than 10,000 times — and maybe 100,000 times — brighter than Jupiter’s, Hallinan said. The reason for this is because LSR J1835+3259 has a magnetic field perhaps 200 times stronger than Jupiter’s, Hallinan added.