Large pairs of planets thought to orbit each other without a star, do not exist after all. That conclude Leiden researchers, after extensive computer modelling and simulations. What the double dots seen by the James Webb Space Telescope are, remains a mystery.
At the end of 2023, the astronomy world was shaken when the James Webb Space Telescope spotted forty double dots in the Orion Nebula. They couldn't be stars - they appeared to be large planets or small brown dwarfs orbiting each other, with no star in sight. A new name was coined: JuMBOs, short for Jupiter-Mass Binary Objects.
The problem? Existing theories of how stars and planets form couldn't account for them. In 2024, three teams of theoretical astronomers proposed possible explanations, and for a while, the mystery seemed solved.
But now, after new simulations by Simon Portegies Zwart and Erwan Hochart (both from Leiden University), those earlier explanations appear to fall apart. What the double dots in the images are, Portegies Zwart doesn't yet know. 'But JuMBOs in the literal sense - they're not.'
What he finds most striking about the outcome is what it shows about how science works. 'You sometimes read negative stories about science and scientists,' Portegies Zwart says, 'but this is a great example of how science corrects itself.'
Scientific article
Why wide Jupiter-mass binary objects cannot form. By: Simon Portegies Zwart & Erwan Hochart. Published in: Nature Astronomy, 18 juli 2025. [original | preprint (pdf)]
This press release originally appeared on astronomie.nl.
