Astronomers have detected a possible “rogue” planetary-mass object with a surprisingly powerful magnetic field travelling through space unaccompanied by any parent star.
The extrasolar object, about a dozen times more massive than Jupiter, is located some 20 light-years from Earth, showed the findings made using the US National Science Foundation’s Karl G. Jansky Very Large Array (VLA) telescope.
“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,” said Melodie Kao from Arizona State University in the US.
Kao led this study while a graduate student at California Institute of Technology (Caltech).
The strange object, called SIMP J01365663+0933473, has a magnetic field more than 200 times stronger than Jupiter’s, according to the study published in The Astrophysical Journal Supplement Series.
The object was originally detected in 2016 as one of five brown dwarfs the scientists studied with the VLA to gain new knowledge about magnetic fields and the mechanisms by which some of the coolest such objects can produce strong radio emission.
Brown dwarf masses are notoriously difficult to measure, and at the time, the object was thought to be an old and much more massive brown dwarf.
Last year, an independent team of scientists discovered that SIMP J01365663+0933473 was part of a very young group of stars.
Its young age meant that it was in fact so much less massive that it could be a free-floating planet — only 12.7 times more massive than Jupiter, with a radius 1.22 times that of Jupiter.
The Caltech team that originally detected its radio emission in 2016 had observed it again in a new study at even higher radio frequencies and confirmed that its magnetic field was even stronger than first measured.
The VLA observations provided both the first radio detection and the first measurement of the magnetic field of a possible planetary mass object beyond our solar system.