Did James Webb Spot Ghosts in Space? New Simulations Suggest These Mysterious ‘Rogue’ Objects May Not Exist
Astronomers were confused when the James Webb Space Telescope (JWST) first saw strange, free-floating pairs of Jupiter-sized objects in 2023. These strange cosmic objects, called "JuMBOs" (Jupiter-mass binary objects), seemed to go against the usual ideas about how planets form because they didn't have a parent star and were drifting through space in tight gravitational embraces. But new computer models suggest that these strange pairs might not even exist. Instead, they could just be illusions, cosmic mirages that even the best telescope in history can't see through.
What Are JuMBOs And Why Do They Puzzle Astronomers?
There are pairs of gas giants called JuMBOs that are locked in orbits around each other. They weigh between 0.7 and 30 times as much as Jupiter. They don't go around a star like planets in our solar system do. Instead, they float around on their own, only being held together by each other at distances of 25 to 400 astronomical units (AU), which is the average distance between the Earth and the Sun (about 93 million miles or 150 million kilometers).
When they were found in the Orion Nebula Cluster, people immediately wanted to know how they came to be. Did they get kicked out of a star system, or did they form like failed stars? Some scientists, like Penn State's Kevin Luhman, raised the question of whether they were real or just optical illusions of faraway background objects that were accidentally lined up in JWST's images.
New Simulations: JuMBOs May Be Cosmic Phantoms
Astrophysicists at the University of Sheffield conducted complex computer simulations to find out if JuMBOs could exist. Richard Parker was in charge of making a nebula that looked like the region where the Orion Nebula was born. They put in 1,500 stars and fake JuMBO pairs. They then used a computer to see how gravity might work over millions of years.
The results were shocking: in crowded star systems, up to 90% of JuMBOs were torn apart in less than a million years. Only half of them lived, even when things were very stable. The farther apart the pairs were, the more likely it was that passing stars would tear them apart.
Parker told Live Science, "Planet-planet binaries are less massive, so they have less energy and are even more likely to be destroyed." The results, which were published in Monthly Notices of the Royal Astronomical Society: Letters, suggest that if JuMBOs were real, they would have to form in huge numbers, much more than current theories say is possible.
Are JWST’s JuMBOs Just an Illusion?
Luhman's earlier doubts are supported by Parker's study. If JuMBOs were as weak as the simulations say, it would be very hard to find a lot of them because they would have to form at an unreasonably high rate. Instead, the simplest answer might be that they aren't rogue planets at all, but just background stars or galaxies that happen to be in JWST's field of view.
Parker said, "This probably adds support to the idea that JuMBOs are background noise." He still says that more study of the original JWST data is needed to end the argument.
What Does This Mean for Planet Formation Theories?
If JuMBOs exist, they would change everything we know about how planets form. Current models say that planets don't form as isolated pairs in deep space, but rather from the disks of gas and dust around young stars. Some theories say they were thrown out of star systems, but it's not very likely that two planets would be thrown out together. Some people think they might be failed stars, but their masses are too low for normal star formation.
If they aren't real, though, it could mean that JWST's unprecedented sensitivity is showing us a new type of observational problem: telling the difference between real cosmic objects and fake alignments.
The Next Steps: Revisiting JWST’s Data
Parker thinks that the answer to this mystery lies in looking at JWST's original observations of the Orion Nebula again. Astronomers might be able to tell if JuMBOs are real or just ghostly artifacts by using better methods to look at the data, maybe paying more attention to distant background objects.
Parker said, "I think the next steps are for someone else to take the original JWST data and look at it again." These strange things in space will stay a mystery until then.
