Above the brown dwarf 18 light years away from our planet, the most powerful and exquisite aurora ever recorded captivated its audience.
And while doing so, it helped weigh in arguments on the nature of brown dwarfs: are they successful planets or failed stars?
As the aurora was shining in hues of green and yellow and red with one million times stronger intensity than Earth’s northern lights, scientists sketched more arguments for why these cold, small and poorly lit celestial bodies outside of the solar system are rather akin to planets than stars.
A few of the most sensitive telescopes were pointed towards the Lyra constellation where LSRF 1835+3259 as this particular brown dwarf is known is located. The National Radio Astronomy Observatory’s Very Large Array Telescope, as well as the Palomar Hale Telescope and the telescope of the W.M. Keck Observatory picked up radio emissions and optical data as the brown dwarf was rotating at an interval of 2.84 hours.
Each radio emission was coupled with an aurora on the surface of the celestial body. As the oxygen, as well as sodium and hydrogen encountered the electrons in the atmosphere of the brown dwarf, the telescopes gathered optical data as well. Hydrogen was the most visible to the telescopes, as it glows a brighter red than any.
In the words of Gregg Hallinan, author of the study and professor of astronomy at the California Institute of Technology:
“In the case of the brown dwarf, the aurora is so much more powerful than anything we’ve seen in our Solar System. Jupiter’s aurorae are 1,000 times more powerful than the Earth’s aurorae. Well, this brown dwarf has aurorae that are at least 10,000 times more powerful than Jupiter’s aurora.”
LSR J1835+3259 is approximately the same size as Jupiter. Yet, its mass is about 80 times bigger. Nevertheless, as it is poorly lit and thus too faint, it is impossible to observe with the naked eye, despite the incredible strength of the aurora.
Despite being massive, the brown dwarf’s status as a celestial body is uncertain. Is it a star? Is it a planet? According to Hallinan, a star is defined by the ability to burn hydrogen at its core.
Brown dwarfs are hardly sufficiently massive to be doing so in their lifetime. However, as planets on which aurorae have been observed are defined by the magnetic fields, and as aurorae have been observed for the first time on a brown dwarf, this could indicate that it is more of a planet than previously thought.
The exciting discovery is also supported by the fact that in the atmosphere of the brown dwarf, clouds were observed as well.
The study was published in the journal Nature.
Photo Credits astro.caltech.edu