Scientists have detected a powerful glowing aurora in the atmosphere of a celestial body known as a brown dwarf, light-years away from our solar system.
The discovery suggests that when it comes to the behavior of their magnetic fields, brown dwarfs — objects that are kind of neither here nor there, like stars in some ways and like planets in others — behave more like Earth than like the sun.
But more broadly, detecting brown dwarf aurorae could have implications for the search for habitable planets outside our solar system, also known as exoplanets, said California Institute of Technology astronomer Gregg Hallinan.
“This tells us we can start looking for this kind of activity in planets,” said Hallinan, lead author of a study describing the aurora, published in the journal Nature.
Stars have magnetic fields. On our sun, these produce solar flares and coronal mass ejections that send radiation known as solar wind out into space, disrupting electronics on Earth and threatening the health of travelers in space.
Planets, meanwhile, have magnetic fields too, which help shield them from that solar wind. Exoplanet hunters often speak of “Goldilocks” planets, positioned just the right distance from their stars to have liquid water on their surface to harbor life. Another possible prerequisite for life might be a magnetic field to shield a planet from dangerous stellar radiation. If you could find an exoplanet with an aurora, Hallinan figures, that might be a good indication that you’ve found a world that has that protection — and is, perhaps, habitable.