JWST spots new rogue worlds

The James Webb Space Telescope (JWST) has spotted 6 new “rogue worlds” in a young star-forming nebula about 1,000 light-years away.

Rogue worlds are objects with planet-like masses that traverse space alone, untethered to a star.

The lightest and most intriguing of these 6 new worlds is surrounded by a disc of space dust the researchers say may be able to form its own planets.

“This might be a nursery of a miniature planetary system, on a scale much smaller than our solar system,” says Dr Aleks Scholz, an astrophysicist at the University of St Andrews, UK, and co-author of the new paper published today in The Astronomical Journal.

The disc hints towards the rogue world’s  star-like origins, as space dust generally spins around the central object in the early stages of star formation. However, as this cloud contracted under gravity it lacked the mass necessary to kick start nuclear fusion, which powers stars.

JWST also discovered a new brown dwarf (an object bigger than the largest gas giant planets but smaller than the smallest stars) with a rare planetary-mass companion.

“It’s likely that such a pair formed the way binary star systems do, from a cloud fragmenting as it contracted,” says senior author Ray Jayawardhana, an astrophysicist at Johns Hopkins University in the US.

“The diversity of systems that nature has produced is remarkable and pushes us to refine our models of star and planet formation.”

Because all the newly discovered worlds are 5-10 times more massive than Jupiter, the researchers think that lighter rogue worlds are more likely to form like planets do.

Coalescing from the discs of gas and dust orbiting around stars, these rogue worlds are eventually ejected from their star systems due to gravitational interactions with other bodies. These free-floating objects blur classifications of celestial bodies because their masses overlap with gas giants and brown dwarfs. Despite being considered rare in the Milky Way galaxy, the new JWST data show they account for about 10% of celestial bodies in the targeted star-forming cluster (NGC1333).