Barnard's Star Exoplanets Deemed Extremely Uninhabitable by Cambridge Study

A new study by researchers at the University of Cambridge confirms that the four rocky exoplanets orbiting Barnard's Star, the Sun's nearest stellar neighbor at just under six light‑years away, are highly inhospitable. The planets, whose masses fall between those of Earth and Mars, orbit extremely close to their red dwarf host—up to ten times closer than Mercury is to the Sun—and are likely tidally locked, presenting permanent day and night sides.

Analysis of the star's chemical composition revealed an unusually high magnesium abundance, which the team says produced large quantities of the mineral periclase (magnesium oxide) on the planets. Unlike Earth's olivine, periclase does not trap water, rendering the worlds exceptionally dry. Combined with weak gravity and intense stellar radiation, the planets are thought to have lost any substantial atmospheres within roughly two billion years, long before the star's current age of about ten billion years. These findings were published in the Monthly Notices of the Royal Astronomical Society, with lead author Xander Byrne noting that the magnesium‑rich environment likely shaped the planets' barren characteristics.