First aurora outside Solar System spotted on a brown dwarf

JC Torres - Jul 30, 2015, 4:30 am CDT
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First aurora outside Solar System spotted on a brown dwarf

Auroras. Borealis in the north, Australis in the south. Who would have thought that finding that same beautiful phenomenon on a celestial body outside our solar system would lead to much excitement. But that is exactly what the brown dwarf LSR J1835 provided astronomers. Located in the Lyra constellation 18 light years away, the small star/big planet exhibited the equivalent of the Aurora, though red in color compared to our own Earth’s green. The thing is, that occurrence has never been recorded outside our Solar System.

As special as we might want it to be, auroras have actually been observed in the planets of our own Solar System. It occurs when charged particles interact with a planet’s atmosphere. In our case, it’s the Sun’s charged particles that interact with the oxygen in our atmosphere, giving off a green hue. But those particles can come from other sources. Jupiter’s aurora, for example, is caused by the particles emitted from volcanoes on its moon, Io.

In this brown dwarf’s case, both the source of the particles and the color of the aurora has sparked theories. The aurora seen was red, indicating that the atmosphere mostly consisted of hydrogen. But what scientists don’t know is where the particles are coming from. They could be from a neighboring planet or moon. Or they could be from the brown dwarf itself.

This goes back to the debate on what a brown dwarf really is. A sort of failed star, it was too small to have become a light source but also too massive to become a planet. It existed in a sort of limbo as far as categorization goes. It also meant that there is no other Sun-like body nearby to give the same effect as our own aurora, limiting the possibilities to those two mentioned.

Proponents for calling brown dwarves as giant planets do consider this discovery enlightening. The presence of aurora all the more confirms the fact that brown dwarves have atmospheres, supporting the claim to consider them big planets instead of small but failed stars.

SOURCE: BBC


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