Astronomers have made a groundbreaking discovery, identifying an unprecedented ‘growth spurt’ in a rogue planet. Unlike planets in our Solar System, these celestial bodies do not orbit stars but instead drift freely through space. Observations using the European Southern Observatory’s Very Large Telescope (ESO’s VLT) have revealed that this free-floating planet is consuming gas and dust at an astonishing rate of six billion tonnes per second. This represents the strongest growth rate ever recorded for any planet, offering valuable insights into the formation and growth of such objects.
“People may think of planets as quiet and stable worlds, but with this discovery, we see that planetary-mass objects freely floating in space can be exciting places,” said Víctor Almendros-Abad, an astronomer at the Astronomical Observatory of Palermo, National Institute for Astrophysics (INAF), Italy, and lead author of the new study.
Unprecedented Growth in the Constellation Chamaeleon
The newly studied object, named Cha 1107-7626, is located approximately 620 light-years away in the constellation Chamaeleon. This rogue planet, with a mass five to ten times that of Jupiter, is still forming and is surrounded by a disc of gas and dust. This material is continuously falling onto the planet in a process known as accretion. However, the team led by Almendros-Abad discovered that the accretion rate is not constant.
By August 2025, the planet was accreting about eight times faster than just a few months earlier, reaching a rate of six billion tonnes per second. “This is the strongest accretion episode ever recorded for a planetary-mass object,” Almendros-Abad noted. The discovery, published in The Astrophysical Journal Letters, was made using the X-shooter spectrograph on ESO’s VLT in Chile’s Atacama Desert. The team also utilized data from the James Webb Space Telescope and archival data from the SINFONI spectrograph on ESO’s VLT.
The Origins of Rogue Planets
The discovery raises intriguing questions about the origins of rogue planets. “The origin of rogue planets remains an open question: are they the lowest-mass objects formed like stars, or giant planets ejected from their birth systems?” asked co-author Aleks Scholz, an astronomer at the University of St Andrews, United Kingdom. The findings suggest that some rogue planets may share a similar formation path to stars, as similar bursts of accretion have been observed in young stars before.
Co-author Belinda Damian, also from the University of St Andrews, explained, “This discovery blurs the line between stars and planets and gives us a sneak peek into the earliest formation periods of rogue planets.” By comparing the light emitted before and during the burst, astronomers gathered clues about the nature of the accretion process. Remarkably, magnetic activity appears to have played a role in driving the dramatic infall of mass, a phenomenon previously observed only in stars.
Implications for Future Discoveries
The team also found that the chemistry of the disc around the planet changed during the accretion episode, with water vapor being detected during the event but not before. This phenomenon had been observed in stars but never in a planet of any kind. Free-floating planets are notoriously difficult to detect due to their faintness, but ESO’s upcoming Extremely Large Telescope (ELT), operating under some of the world’s darkest skies, could change that.
Amelia Bayo, a co-author and ESO astronomer, remarked, “The idea that a planetary object can behave like a star is awe-inspiring and invites us to wonder what worlds beyond our own could be like during their nascent stages.”
Looking Ahead
This research, presented in a paper titled “Discovery of an Accretion Burst in a Free-Floating Planetary-Mass Object,” highlights the potential for future discoveries. ESO’s ELT, with its powerful instruments and giant main mirror, will enable astronomers to uncover and study more of these solitary planets, enhancing our understanding of their star-like characteristics.
The European Southern Observatory (ESO) continues to facilitate groundbreaking astronomical research, providing scientists worldwide with the tools to explore the universe’s secrets. As we look to the future, the potential for new discoveries about rogue planets and their formation processes remains vast, promising to reshape our understanding of planetary science.
