ESO VLT team reports planetary-mass exosatellite around brown dwarf in CD-35 2722

Astronomers using the European Southern Observatory's Very Large Telescope report evidence of a Jupiter-mass object orbiting a brown dwarf that itself circles the star CD-35 2722, according to SciTechDaily's write-up of a Nature paper led by ESO student Kevin Hoy. Unlike Solar System moons, the object does not orbit a planet. The researchers call it an exosatellite: at least Jupiter's mass circling a brown dwarf more than 30 times Jupiter's mass, while the host star has about half the Sun's mass. Hoy and collaborators used the CRIRES+ instrument and the radial velocity method, detecting slight wobbles in the brown dwarf attributed to the companion's gravity. SciTechDaily notes that more than 6,000 exoplanets are known but no exomoon has been confirmed with confidence; a recent HD 206893 report suggested a satellite without a firm detection. Collaborator Alice Zurlo of YEMS and Universidad Diego Portales described the system as a plausible first exosatellite detection. The paper lists DOI 10.1038/s41586-026-10751-w.