Barnard’s Star’s Four Close‑In Exoplanets Found to Be Dry and Atmosphereless

A team of astronomers from the University of Cambridge has produced the most detailed description to date of the four small exoplanets orbiting Barnard’s Star, the nearest star to the Sun after Alpha Centauri. Discovered in 2025, the planets are smaller than Earth and Venus but larger than Mars. Spectroscopic analysis of the host star reveals an unusually high magnesium content, leading the researchers to conclude that the planets are rich in the rare mineral periclase, which is ineffective at retaining water.

Because the planets orbit extremely close to Barnard’s Star— the outermost world circles ten times nearer than Mercury does the Sun—their atmospheres are expected to have been stripped away within about two billion years, far shorter than the ten‑billion‑year age of the system. Tidal locking leaves each planet with a permanent day side and night side, while an orbital resonance of 9:12:16 stabilises the configuration. The findings, published in the Monthly Notices of the Royal Astronomical Society, highlight the harsh, likely lifeless conditions of these worlds and suggest they could serve as benchmarks for future observations with the James Webb Space Telescope and upcoming extremely large ground‑based telescopes.