Overview
- A team led by Kevin Hoy published a Nature paper on July 22 reporting a companion with a minimum mass of about 0.9 Jupiter orbiting the brown dwarf CD‑35 2722 b on a roughly 170‑day period.
- The signal comes from 23 high‑precision radial‑velocity measurements taken with ESO’s Very Large Telescope and the CRIRES+ spectrograph between October 2023 and February 2026 that show a periodic wobble in the brown dwarf’s spectrum.
- Because radial velocity gives only a minimum mass, the companion could be more massive than reported and some experts say the data could instead reflect a three‑body configuration or a binary of substellar objects rather than a true moon.
- The discovery highlights a classification problem: the object orbits a brown dwarf that itself orbits a star, so researchers use the neutral term “exosatellite” and debate whether the body formed by moon‑like core accretion or by direct collapse like a star.
- Definitive answers will require follow‑up using complementary methods such as astrometry and direct imaging and next‑generation facilities like the ELT and space missions that can better constrain mass, orbit and formation history.