Astronomers using the European Southern Observatory's Very Large Telescope (ESO's VLT) have witnessed an extraordinary growth spurt in a free-floating planet, observing it accumulate mass at a rate of six billion tonnes per second - the fastest accretion ever recorded for a rogue planet or any planet to date.
Rogue planets drift through space untethered to any star. The newly studied objec by Erica Marchand
Paris, France (SPX) Oct 06, 2025
Astronomers using the European Southern Observatory's Very Large Telescope (ESO's VLT) have witnessed an extraordinary growth spurt in a free-floating planet, observing it accumulate mass at a rate of six billion tonnes per second - the fastest accretion ever recorded for a rogue planet or any planet to date.
Rogue planets drift through space untethered to any star. The newly studied object, officially named Cha 1107-7626, is located 620 light-years away in the constellation Chamaeleon and is estimated to have five to ten times the mass of Jupiter. It remains in formation, surrounded by a dense disk of gas and dust from which it continues to feed.
"This is the strongest accretion episode ever recorded for a planetary-mass object," says lead author Victor Almendros-Abad of the Astronomical Observatory of Palermo, National Institute for Astrophysics (INAF), Italy. By August 2025, the team observed the planet's growth rate increasing eightfold compared to earlier in the year.
The team employed ESO's X-shooter spectrograph on the VLT in Chile's Atacama Desert, supported by observations from NASA's James Webb Space Telescope and archival data from ESO's SINFONI spectrograph. The results reveal not only a fluctuating accretion rate but also a changing chemical signature - including the sudden appearance of water vapor during the burst, a phenomenon previously observed only in stars.
"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?" notes co-author Aleks Scholz of the University of St Andrews, UK. The new data suggest that at least some rogue planets may grow in star-like bursts, blurring the distinction between stars and planets.
Magnetic fields appear to drive the dramatic mass infall, similar to the mechanisms powering stellar accretion. "This discovery blurs the line between stars and planets and gives us a sneak peek into the earliest formation periods of rogue planets," adds co-author Belinda Damian, also from St Andrews.
Future observations with ESO's upcoming Extremely Large Telescope (ELT) are expected to reveal more of these elusive, star-like planets, potentially transforming our understanding of how such cosmic wanderers are born. As ESO astronomer Amelia Bayo puts it, "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."
Research Report:Discovery of an Accretion Burst in a Free-Floating Planetary-Mass Object
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