Six billion tons a second. That is the rate at which a rogue planet is consuming gas and dust right now. Astronomers have never seen anything like it. The feeding frenzy outpaces anything recorded in planets or stars, breaking every rule in the book and forcing a re-examination of what worlds are capable of.
The planet has a name only a scientist could love: Cha 1107-7626. It lies 620 light years away in the constellation Chamaeleon. It is not bound to any star. It drifts through interstellar space like an orphan, carrying only a disk of gas and dust that surrounds it. That disk has now become fuel for the most violent growth spurt ever recorded in an object of its size. With a mass estimated between five and ten Jupiters, this world sits at the boundary between planet and brown dwarf. Yet its behavior has proven more violent than either.
The eruption began in mid-2025. Observations with the Very Large Telescope in Chile showed faint, ordinary spectra in April and May. By June the story had changed. Accretion lines flared, light surged, and the planet entered a runaway feeding phase. By July the feeding rate had risen six- to eight-fold. By August the pace reached six billion tons per second, and it did not stop. When the observing campaign ended, the accretion was still at maximum. The burst lasted at least two months, making it the longest and strongest planetary growth episode ever seen.
The numbers tell the scale of the event. At the peak, the planet was swallowing matter equal to the mass of Mount Everest every fraction of a second. The optical continuum increased three to six times, making the object up to two magnitudes brighter in the R band. Infrared flux climbed by 10 to 20 percent. The surrounding disk shifted in chemistry. Water vapor appeared in emission for the first time. Hydrocarbon lines altered shape. The entire environment was rewritten in real time by the violence of the feeding burst.
Spectra revealed the real shock. The hydrogen H-alpha line split into a double-peaked profile with redshifted absorption. This is the fingerprint of magnetospheric accretion, the process in which strong magnetic fields funnel gas onto a body in hot streams. It has been seen in stars. It has been seen in brown dwarfs. It has never been caught in an object with the mass of a planet. Yet here it was, a five- to ten-Jupiter-mass rogue channeling gas like a newborn sun.
The detail matters. The redshifted absorption was shifted by 20 to 40 kilometers per second, clear evidence of infalling gas projected against the hot spots of impact. The change was not a flicker. It held across months of observations. The planet was not varying in a simple rotational cycle. It was sustaining a violent accretion mode, consistent with unstable funnel flows, the kind that can only exist with strong magnetic activity. This proves that even planetary bodies can carry magnetic fields capable of powering stellar-like accretion.
The chemical evidence added to the shock. The mid-infrared spectrum taken by the James Webb Space Telescope showed a new 6.6 micron feature, best explained as water vapor emission. Before the burst, there was none. During the burst, it appeared strongly. This is the first time water vapor has been seen triggered by planetary accretion. Alongside it, hydrocarbon features shifted. The blue peak of the methane band grew relative to the red. The entire balance of carbon chemistry changed as the disk was heated. This shows the violent feeding event reshaped not just the brightness but the molecular structure of the environment.
Comparisons underline how extreme this is. Young stars undergoing EXor outbursts show similar behavior: sudden increases in brightness, optical surges, double-peaked hydrogen lines, and chemical changes in their disks. Cha 1107-7626 shows all of them. That makes it the first planetary-mass object confirmed to undergo an EXor-type burst. It is behaving like a star. The only difference is its size. Where EX Lupi brightened by two magnitudes in 2022, this rogue planet matched that amplitude. Where young stars increased their accretion rates seven-fold, this world did the same. The boundary has been crossed.
The rate itself is a record breaker. During the burst the accretion reached ten to the minus seven Jupiter masses per year. That is the highest ever measured in a planet. For comparison, the embedded protoplanets directly observed in disks around stars feed at least twenty times more slowly. This rogue planet feeds like a monster, faster than anything in its category and even rivaling low-mass stars.
Archival spectra add more weight. In 2016, data show that the planet was also in a high accretion state. That suggests the bursts may repeat every decade or so. If confirmed, this means Cha 1107-7626 is a recurring eruptive object. That places it in the same class as EXor stars, but at planetary mass. It makes this the first confirmed recurring eruptive planet, a category that did not exist until now.
The mechanics are stark. The disk surrounding the planet heats under the stress of infall. The optical continuum rises by a factor of six. The mid-infrared shows a 20 percent increase, consistent with a temperature jump of less than 100 K but spread across the disk. The hydrogen lines broaden and deepen. The H-alpha profile grows wings and develops redshifted absorption. Paschen lines strengthen, Brackett lines appear, water emerges. The violence of the burst changes everything measurable in the spectrum.
The duration sets it apart. Ordinary variability in young stars produces accretion changes by factors of two or three, lasting days to weeks. This rogue planet held a six- to eight-fold increase for more than two months. That rules out surface flickering or rotational cycles. The rotation of a body this size is likely one to four days. The burst lasted more than fifteen rotations. It was not a cycle. It was a structural change in how the body feeds.
The fact that it is free-floating makes it even more dramatic. Planets in orbit around stars are fed by circumstellar disks. They grow in protected nurseries. This world has no host star, no system, no nursery. It is alone, and yet it still carries a disk and still erupts in violent growth. That fact alone challenges models of planetary formation. It strengthens the case that at least some rogue planets are born like stars, collapsing from isolated gas clouds, carrying disks, and undergoing eruptive growth. The alternative, that they were ejected from planetary systems, cannot easily explain a recurring accretion disk feeding episode.
The discovery was made possible by the instruments aimed at it. The VLT’s X-shooter spectrograph captured visible to near-infrared spectra across multiple epochs. JWST’s NIRSpec and MIRI added high-resolution infrared coverage, confirming the molecular features and the mid-infrared changes. Together the two facilities delivered an uninterrupted view from ultraviolet to 12 microns, enough to track both the hot continuum and the chemical fingerprint of the disk. Without this coverage, the burst would have looked like an ordinary brightening. With it, the scale of the feeding was revealed.
By every measure, this is the most extreme planetary accretion event ever seen. The fastest feeding rate, the strongest accretion burst, the clearest double-peaked hydrogen signature, the first water vapor detection, the brightest continuum surge. Each one is a record. Combined, they rewrite what is possible for planetary bodies.
The event has not ended. The last data collected showed the accretion still increasing. The hydrogen lines were at their strongest, the continuum still elevated, the water vapor still present. How long the burst will continue is unknown. It may last four months, six months, or more. It may collapse suddenly. It may repeat again in ten years. Only continued monitoring will answer that. But the fact remains: for at least two months a rogue planet has been feeding at a rate unmatched by anything of its kind.
Future telescopes will change the landscape further. The Extremely Large Telescope, under construction in Chile, will have the power to survey wide fields with unprecedented sensitivity. It will be able to find many more rogue worlds. If Cha 1107-7626 is not unique, then the galaxy could be full of orphan planets undergoing hidden eruptions. These objects are faint, but when they flare they reveal themselves. The ELT will catch them.
For now, one object holds the crown. Cha 1107-7626 is a rogue planet feeding at six billion tons per second. It is the fastest growing planet ever recorded. It is the first confirmed planetary-mass EXor. It is the clearest evidence that planets can behave like stars. This is the benchmark for planetary violence, and it will remain so until something even more extreme is found.
Six billion tons a second. The number speaks for itself.
Source:
Almendros-Abad et al., The Astrophysical Journal Letters (2025), https://doi.org/10.3847/2041-8213/ae09a8
