The candidate is at least as heavy as Jupiter. And it may be a moon.
Astronomers studying the CD-35 2722 system have found signs of a body with at least the mass of Jupiter. It appears to orbit a brown dwarf of roughly 37 Jupiter masses.
If it holds up, this would be an exomoon, meaning a natural satellite outside the Solar System. That’s why the scientists call it a possible exomoon. Nobody has confirmed it yet.
A moon around something that isn’t quite a star
Brown dwarfs sit in an awkward middle category. They’re heavier than planets, but they don’t have enough mass to keep up the nuclear reactions that make stars shine.
So the possible moon is odd twice over. It looks like it has the mass of a planet, yet it orbits a brown dwarf instead of a planet.
How they caught the wobble
The team used the European Southern Observatory’s Very Large Telescope and its CRIRES+ instrument. They relied on the radial velocity method, which picks up very small shifts in the brown dwarf’s motion.
Those shifts may come from the gravitational pull of the body in orbit around it. They’re the main evidence that the body exists at all.
Why the label is still up for grabs
There are two open problems. The object’s existence hasn’t been confirmed, and its large mass makes it hard to say whether it should count as a moon or a planet.
The study was published in the journal Nature.
