It’s at least as massive as Jupiter, and it might be a moon.
While studying the CD-35 2722 system, astronomers picked up evidence of a body with a mass of at least one Jupiter. It seems to be orbiting a brown dwarf that weighs in at about 37 Jupiter masses.
Should the finding stand, the object would be an exomoon: a natural satellite beyond the Solar System. Because no one has confirmed it so far, the researchers describe it as a possible exomoon.
Orbiting an object that falls short of being a star
Brown dwarfs occupy an in-between class. They outweigh planets, but they lack the mass needed to sustain the nuclear reactions that make stars shine.
That makes the candidate moon strange on two counts. Its mass looks like a planet's, and the thing it circles is a brown dwarf, not a planet.
Spotting the wobble
To make the detection, the team turned to the European Southern Observatory’s Very Large Telescope and its CRIRES+ instrument. They used the radial velocity method, which detects tiny changes in the brown dwarf’s movement.
The gravitational tug of an orbiting body could be behind those changes. They’re the primary evidence that the object is there at all.
Moon or planet? Still undecided
Two questions remain open. Nobody has confirmed the object exists yet, and because it’s so massive, it’s difficult to decide whether it should count as a moon or a planet.
The research appeared in the journal Nature.