Rogue planet accretes mass at record 6 billion tonnes per second
Astronomers have observed a free-floating planet gaining mass at an unprecedented rate as it plows through the interstellar medium. The rogue world, similar in size to Jupiter, is adding 6 billion tonnes every second in what researchers call a record growth spurt. This discovery highlights how such planets can evolve independently of stars.
In a striking example of cosmic opportunism, a rogue planet wandering through the galaxy has been caught in the act of rapid expansion. Unlike planets bound to stars, this free-floating world moves solo through the vast emptiness of space, scooping up gas and dust from the interstellar medium in its path.
The observation comes from a study published in the Astrophysical Journal Letters, detailing data from the Atacama Large Millimeter/submillimeter Array (ALMA) telescope. Researchers identified the planet, dubbed a 'super-Jupiter' with about 13 times the mass of our own Jupiter, hurtling along at speeds exceeding 30 kilometers per second. At this velocity, it compresses and heats the surrounding gas, leading to accretion at a rate of 6 billion tonnes per second—equivalent to the mass of a small mountain added every moment.
"This is an extraordinary rate of growth, unlike anything we've seen before for a planet not orbiting a star," said lead researcher Aaron Skinner of the University of Warwick. The process resembles how stars form but on a planetary scale, suggesting that rogue planets could bulk up significantly over billions of years, potentially evolving into brown dwarfs.
Background context reveals that rogue planets are ejected from their stellar systems early in their formation, numbering in the billions across the Milky Way. Previous models predicted slow growth for these nomads, but this event challenges those assumptions. The planet's location is roughly 400 light-years away in the constellation Orion, observed in infrared and submillimeter wavelengths to detect the glowing envelope of accreting material.
While the growth spurt is temporary—lasting perhaps a few million years as the planet traverses a dense gas cloud—its implications are broad. It offers insights into planet formation in isolation and the dynamics of the interstellar medium. No direct contradictions appear in the data, though future observations with the James Webb Space Telescope could refine the mass gain estimates.
This discovery underscores the dynamic nature of our galaxy, where even the most isolated worlds can thrive through relentless motion.