Astronomers have reported the possible detection of the first natural satellite beyond the Solar System. The object orbits a brown dwarf in the CD-35 2722 system.
The system is located approximately 70–73 light-years from Earth. The central star has a mass of about half that of the Sun, while the brown dwarf CD-35 2722 B has about 35–37 Jupiter masses.
The observations were carried out from October 2023 to February 2026 using the CRIRES+ infrared spectrograph on ESO's Very Large Telescope in Chile. The scientists recorded a modulation of the radial velocity with a period of about 170 days.
The most probable model points to a satellite with a minimum mass of 0,9 Jupiter masses and an orbital period of 171 day. The object orbits not around a planet, but around a brown dwarf.
The status of the find remains a matter of debate. The candidate's mass is comparable to Jupiter's, so it is difficult to classify it unambiguously as a moon or a planet. The researchers prefer the term "exomoon."
The discovery was made by an international team led by Kevin Hoy. The results have been published in the journal Nature. If confirmed, this will be the first case of detecting a natural satellite outside our system.
What will this discovery say about the diversity of celestial architectures beyond the Solar System? For now, the scientists emphasise that the system is young, about 150 million years old, and requires further observations.
The radial velocity method, applied here for the first time to search for a satellite around a brown dwarf, opens up new possibilities. Future instruments such as the Extremely Large Telescope will help refine the details.
