Astronomers detect possible first exomoon orbiting a brown dwarf

Astronomers using the European Southern Observatory’s Very Large Telescope have identified evidence of a massive object that may be the first natural satellite discovered outside our Solar System. The object, described as a possible exomoon or exosatellite, is located in the CD-35 2722 system.

Unlike moons in our Solar System, this object orbits a brown dwarf—a celestial body more massive than a planet but lacking the mass to sustain nuclear fusion like a star. The candidate object has a mass at least equal to Jupiter, while the brown dwarf it circles is approximately 37 times the mass of Jupiter.

Researchers utilized the radial velocity method via the CRIRES+ instrument to detect gravitational tugs on the brown dwarf. Due to the object's immense size, scientists noted that the discovery challenges existing definitions of planets and moons. The study has been published in the journal Nature.