Astronomers Discover Incredible Magnetism in Rogue Planet | NOVA


Twenty light-years away, a massive magnetic sunless exoplanet generates brilliant auroras that would shame Earth’s Northern Lights.

According to a recent

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study in

The Journal of Astrophysics

, the rogue planet has a magnetic field almost 4 million times stronger than that of Earth and a mass 12.7 times the size of Jupiter. This discovery marks the first time that radio observations and magnetic field measurements have been made on such a body and opens the door to future perspectives on the exploration of exoplanetary magnetic fields.

Here’s Jake Parks, reporting for Astronomy how the unattached planet, named SIMP J01365663 + 0933473, will help astronomers learn more about the universe:

“This particular object is exciting because studying its dynamo-magnetic mechanisms can give us new information on how the same type of mechanisms can work in extrasolar planets,” said [Arizona State University’s Melodie] Kao. “We believe that these mechanisms may work not only in brown dwarfs, but also in gas and terrestrial giant planets.”

How the sunless planet has such strong auroras, similar to those seen in the giant planets of our own solar system, remains a mystery.

The auroras on Earth, known as the northern and southern lights, rely on a constant flow of energetic charged particles from the Sun, called the solar wind. When these particles approach Earth, they are attracted to the poles of our planet by our global magnetic field. Eventually they hit molecules in the upper atmosphere and – bam! – generate beautiful beams of multicolored light.

Jupiter, however, is too far from the Sun to be so strongly affected by solar winds. Its charged particles probably originate from its moon Io, which is the most volcanically active world in the solar system. Researchers believe that SIMP, which has a magnetic field 200 times stronger than that of Jupiter, may also have a moon or another planet as its source of particles.

The discovery may also illustrate a new way to find other elusive exoplanets without a parent star, by tracking them through their auroral radio show.

Photo credit: Caltech / Chuck Carter; NRAO / AUI / NSF


Arline J. Mercier