Planet-sized object has a powerful magnetic field
The 'world' straddles the boundary between a giant gas planet and a brown dwarf
A ‘rogue’ planetary-mass object which is 20 light years away from Earth has a surprisingly strong magnetic field, astronomers have discovered. The object – called SIMP J01365663+0933473 – has a magnetic field more than 200-times stronger than Jupiter's but, since it is only 12.7-times more massive than the gas giant, it is still not known whether it is a planet or a star.
Quite how the object is able to maintain such power is now being investigated, with the National Radio Astronomy Observatory saying the study of the magnetic dynamo mechanisms “can potentially help us understand magnetic processes on both stars and planets”. It was observed using the Very Large Array, making it the first radio-telescope detection of a planetary-mass object beyond our Solar System. But it also has other unusual properties, not least the fact that it is travelling alone, unaccompanied by a parent star.
“This object is right at the boundary between a planet and a brown dwarf, or ‘failed star’,” explains Melodie Kao, who led the study while a graduate student at Caltech, and is now a Hubble postdoctoral fellow at Arizona State University. It was originally detected in 2016 and it has a surface temperature of 825 degrees Celsius (1,517 degrees Fahrenheit), compared to the Sun's 5,500 degrees Celsius (9,932 degrees Fahrenheit).