Twenty light-years away, a massive, magnetic exoplanet without a sun is generating brilliant auroras that would put Earth’s northern lights to shame.
According to a recent study in The Astrophysical Journal, the rogue planet has a magnetic field almost 4 million times stronger than Earth’s and a mass 12.7 times the size of Jupiter. The discovery marks the first time radio observations and magnetic field measurements have been made of such a body and opens the door for future insights into exploring exoplanetary magnetic fields.
Here’s Jake Parks, reporting for Astronomy on how the untethered planet, named SIMP J01365663+0933473, will help astronomers learn more about the universe:
“This particular object is exciting because studying its magnetic dynamo mechanisms can give us new insights on how the same type of mechanisms can operate in extrasolar planets,” said [Arizona State University’s Melodie] Kao. “We think these mechanisms can work not only in brown dwarfs, but also in both gas giant and terrestrial planets.”
How the sunless planet has such strong auroras, similar to those seen in our own Solar System’s giant planets, remains a mystery.
Auroras on Earth, known as the northern and southern lights, rely on a constant flow of energetic charged particles coming from the Sun, called solar wind. When these particles near Earth, they’re pulled toward the poles of our planet by our global magnetic field. Eventually, they hit molecules in the upper atmosphere and—bam!—generate beautiful beams of multi-colored light.
Jupiter, however, is too far from the Sun to be as strongly effected by solar winds. Its charged particles likely come from its moon Io, which is the most volcanically active world in the Solar System. Researchers believe that SIMP, which has magnetic field 200 times more powerful than Jupiter’s, may also have a moon or other planet as its particle source.
The discovery may also illustrate a new way to find other elusive exoplanets with no parent star—by tracking them through their auroral radio emission.