The discovery of ‘JuMBO’ in the Orion Nebula will rewrite theories about planets and star formation

An image of the Orion Nebula in one of the filters used in this study. 2,400 images in 12 filters make up the observations of the region that the study is based on.Image Credit: NASA, ESA, CSA / Science leads and image processing: M. McCaughrean, S. Pearson

Astronomers report the surprising discovery of binary objects with the mass of Jupiter

JWST observations have now revealed the presence of microscopic objects in the Trapezoidal Cluster, located on land in the Orion Nebula. It is only 300,000 years old and provides insight into the formation of stars, brown dwarfs and planets. Brown dwarfs nominally have masses ranging from 13 to 80 times that of Jupiter. A higher mass stellar object has a core dense enough to convert hydrogen into helium. It’s a star. Anything lower than that can’t even fuse deuterium, leaving them just giant masses of gas.

Another approach to classifying these objects is how they form. Stars form from gas clouds that collapse on themselves when you put too much gas in too small a space. For this to happen, you need refrigerant gas. Hot air disperses and cold air condenses. But things can’t be too big or too small, otherwise the gas can’t cool and stellar objects can’t form. In the Orion Nebula, observations show that in fact, with the right shocks and interactions, you can eventually form objects about three times the mass of Jupiter.

New observations suggest we could go much lower. The team reports the presence of objects as small as 0.6 times the mass of Jupiter. That’s twice the mass of Saturn. These objects could be rogue planets – free-floating – that escape the stars they formed around through a dramatic interaction. The alternative, which currently has no theoretical explanation, is that these stars form as stars.

“If you had an interaction in a disk, maybe you could throw in one of those planets. So we think that in regions like Orion, there should be some kind of floating planets, which initially formed in disks,” said co-author Dr. Mark McCaughrean, senior advisor for science and technology. exploration at the European Space Agency.

“The real problem is that about 40 of them are binary. They go in pairs. And so how do you eliminate two things that still exist together in a violent event like this? I mean, I’m an observer: that’s exactly what I want to do, analyze things for the theorists!

Observations that 9% of these planet-sized objects are binaries suggest that they must have formed in a completely different way than planets of the same mass. These Jupiter-mass binary objects (JuMBOs) challenge our current theories about star and planet formation. How big can an object that looks like a star be? The team believes it will be near the bottom line. JWST’s sophisticated observations have revealed no hint of a population of even smaller yet-to-be-discovered objects. What is certain is that these small objects look nothing like stars. But to understand them better, additional observations are needed.

“To get more information, we need to go back to JWST and get real spectra from it. And we’ll do that in March. We’ve secured time on the observatory.” » Dr. McCaughrean told IFLScience. Understanding these objects in the context of rogue planets is an open question. Do they make up a significant portion of all the planets floating freely around the galaxy, not associated with a star? We don’t know yet, which may depend on whether the conditions that form them are rare or not. The team doesn’t think there’s anything special about Trapezium – they’ve seen these objects in other JWST images. But until there is a better understanding, the questions remain unanswered.