Barnard’s Star exoplanets deemed dry and lifeless

A Cambridge research team has refined the characterisation of the four small planets orbiting Barnard’s Star, the Sun’s nearest neighbour after Alpha Centauri. Discovered in 2025, the worlds are larger than Mars but smaller than Earth and Venus. Spectroscopy of the host star shows an unusually high magnesium‑to‑silicon ratio, leading the authors to infer a mantle dominated by periclase (magnesium oxide), a mineral that does not retain water. Their tight, tidally‑locked orbits – the outermost planet lies ten times nearer to its star than Mercury does to the Sun – expose the bodies to intense radiation and a rapid loss of any primitive atmosphere, estimated to have occurred within about two billion years, far earlier than the system’s ten‑billion‑year age. The planets are locked in a 9 : 12 : 16 orbital resonance that stabilises the configuration. The study, published in *Monthly Notices of the Royal Astronomical Society*, concludes the planets are extremely dry, radiation‑burnt and unlikely to support carbon‑based life, and suggests they will serve as benchmarks for forthcoming James Webb and extremely large‑telescope observations.