Using publicly available data from NASA's Chandra X-ray Observatory archive, researchers reported finding 84 "hypersoft X-ray sources" across six galaxies, according to a NASA release dated September 9, 2026. The objects emit unusually low-energy X-rays but intense ultraviolet radiation, a combination the team said it had not seen before. Two of the galaxies studied were spirals, M31 (Andromeda) and M101 (Pinwheel); the other four were ellipticals. The sources appeared in low-energy Chandra images but vanished at higher energies.

In the paper, published Wednesday in Nature Astronomy, the researchers said it remains unclear what kind of objects produce the emission. They suggested the sources most likely involve a black hole, neutron star or white dwarf pulling material from a companion star. Study leader Mustafa Muhibullah of the University of Alabama said the team's next step was to try to determine what the objects are. The release noted that the discovery could bear on two open questions: the progenitors of Type Ia supernovae, used to measure cosmic expansion, and what strips electrons from gas between stars in some galaxies. Co-author Jimmy Irwin said finding a way to spot Type Ia explosions before they occur would be important.