Exosatellite Discovery Around Brown Dwarf in CD-35 2722 System

Astronomers using the Very Large Telescope (VLT) at the European Southern Observatory in Chile have reported a Jupiter‑mass object orbiting a brown dwarf that itself circles a star about half the Sun’s mass. The system, designated CD‑35 2722 and located roughly 72 light‑years from Earth, represents a three‑tiered arrangement that researchers describe as a possible first exosatellite (or exomoon) beyond the Solar System.

The detection relied on radial‑velocity measurements with the CRIRES+ spectrograph, a technique that tracks subtle wobbles in the brown dwarf’s motion. Lead author Kevin Hoy, an ESO student in Santiago, and collaborator Alice Zurlo of Universidad Diego Portales presented the findings in Nature, noting that the object's mass and orbital context blur traditional definitions of planets and moons. While the object is massive enough to be called a planet, it does not orbit a star directly, prompting the team to label it an “exosatellite.” The discovery follows more than 6,000 confirmed exoplanets but no unequivocal exomoon, and it may guide future searches for similar distant satellites.