Chandra archive reveals 84 mysterious cosmic objects

Astronomers using archived data from NASA's Chandra X-ray Observatory have identified 84 objects that behave unlike any previously known class of cosmic source, according to a study published on September 9, 2026 in the peer-reviewed journal Nature Astronomy. The researchers have named them hypersoft X-ray sources because they emit unusually low-energy X-rays while apparently producing large amounts of energetic ultraviolet radiation. The team, led by Mustafa Muhibullah of the University of Alabama, made the discovery by combing through the publicly available Chandra archive rather than through new observations. They searched six galaxies, including the spiral Andromeda galaxy (M31) and Pinwheel galaxy (M101), along with the elliptical galaxies NGC 4472, NGC 3115, NGC 4697 and NGC 3379. The objects were identified by finding sources that appeared in Chandra images taken at the lowest X-ray energies but vanished in higher-energy images, indicating they emit far more low-energy X-rays than high-energy ones.