Astronomers have caught a young rogue planet in the midst of an unprecedented eating binge, consuming six billion tons of gas and dust every second in what represents the fastest growth rate ever measured for any kind of planet.
The object, designated Cha 1107-7626, floats freely through space about 620 light-years from Earth without orbiting any star. Over several months beginning in June 2025, the planet experienced what researchers are calling an accretion burst, dramatically ramping up its consumption of material from the disk of gas and dust that surrounds it.
A Glimpse Into Planetary Infancy
The discovery offers rare insight into how these isolated worlds behave during their formative years. Ray Jayawardhana, Provost and Professor at Johns Hopkins University and senior co-author of the study, noted the significance of capturing this event in real-time.
We’ve caught this newborn rogue planet in the act of gobbling up stuff at a furious pace. Monitoring its behavior over the past few months, with two of the most powerful telescopes on the ground and in space, we have captured a rare glimpse into the baby phase of isolated objects not much heftier than Jupiter.
The planet itself weighs in at five to 10 times Jupiter’s mass. Using the European Southern Observatory’s Very Large Telescope and the James Webb Space Telescope, researchers tracked dramatic changes in the planet’s appearance and behavior. At the burst’s peak in August, the accretion rate had jumped to roughly eight times what it was in the months prior.
Lead author Victor Almendros-Abad, an astronomer at the Palermo Astronomical Observatory in Italy, emphasized the unusual nature of the finding.
This is the strongest accretion episode ever recorded in a planetary-mass object. 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.
The observations revealed something else unexpected: the planet’s magnetic field appears to funnel material from the disk’s inner edge directly onto the planet’s surface, creating a bright hot spot. This process, previously seen only in young stars, suggests these rogue worlds form through mechanisms remarkably similar to stellar birth.
Chemistry in Flux
The burst also triggered chemical changes in the surrounding disk. Water vapor appeared during the growth spurt but was absent before, detected by instruments aboard the James Webb Space Telescope. The disk, which already showed signs of carbon-rich chemistry with emissions from methane and ethylene, underwent shifts in its molecular composition as temperatures rose from the additional heating.
In optical wavelengths, the planet brightened by a factor of three to six, equivalent to becoming 1.5 to 2 magnitudes brighter. The planet’s hydrogen-alpha emission line developed a distinctive double-peaked profile with red-shifted absorption, a telltale signature of magnetospheric accretion where cool gas falls toward the surface through magnetic field lines.
The event lasted at least two months and was still ongoing when observations concluded in late August 2025. Intriguingly, archival data from 2016 show similarly high accretion levels, hinting that Cha 1107-7626 may experience these bursts repeatedly, perhaps on timescales of several years.
Jayawardhana added that the findings underscore fundamental similarities between rogue planets and young stars, with implications for understanding how giant planets can form directly from collapsing clouds rather than building up slowly in disks around stars. The discovery marks Cha 1107-7626 as the first planetary-mass object identified as an EXor, a class of young stellar objects known for episodic accretion bursts.
The research appears in the Astrophysical Journal Letters. While accretion variability is common in young stars, changes of this magnitude over months are unusual and provide a window into the tumultuous early lives of worlds that wander the galaxy alone.
The findings have been accepted for publication in The Astrophysical Journal Letters. More details: ESO Science Paper 2516
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