A stray "planet" outside the solar system is baffling astronomers with its unusually large size and surprisingly strong magnetic field.

Located 20 light-years from Earth, it is drifting through space without a parent star and orbit.

The hefty object, dubbed as SIMP J01365663+0933473, is roughly a dozen times larger than Jupiter, according to the National Radio Astronomy Observatory. It also features a magnetic field over 200 times stronger than the gas giant's.

Straddling The Line Between Planet And Dwarf

In new research published in The Astrophysical Journal, scientists describe the massive object as one that's between a planet and a brown dwarf.

"This object is right at the boundary between a planet and a brown dwarf, or 'failed star,' and is giving us some surprises that can potentially help us understand magnetic processes on both stars and planets," study lead Melodie Kao, a Hubble Postdoctoral Fellow at Arizona State University, explains in a statement.

Brown dwarves are much too large to be called planets but also too small for the fusion of hydrogen in its core, which is a primary function of stars. Some are found to feature prominent auroras, but the origins of these have not yet been conclusively determined.

Determining the exact boundary between the classifications of planet and brown dwarf is still under debate, but many scientists use the mass 13 times the size of Jupiter.

This puts SIMP J01365663+0933473 right at the boundary.

The History Of The Rogue Planet

The strange object was discovered in 2016 and originally believed to be a very old brown dwarf.

However, in research back in 2017, the SIMP J01365663+0933473 was found to be very young at just 200 million years old. Scientists also determined the size of the free-floating object to be much smaller than previously believed at 12.7 times the size of Jupiter.

The rogue's magnetic field has also been measured and appear to be a lot stronger.

VLA Observations

The new observations of the free-floating planet were made using the Very Large Array. It marks the first ever radio detection and the first measurement of the magnetic field of a planetary mass object outside the solar system.

It is a significant milestone, as it demonstrates that radio telescopes can spot new planets outside the solar system by their auroras.

"Detecting SIMP J01365663+0933473 with the VLA through its auroral radio emission also means that we may have a new way of detecting exoplanets, including the elusive rogue ones not orbiting a parent star," Gregg Hallinan of Caltech says.