Astronomers have discovered 84 unusual X-ray sources called "hypersoft sources" in six different galaxies by reanalyzing data from NASA's Chandra X-ray telescope, which has been orbiting Earth since 1999. These objects emit very soft X-rays, which are difficult to detect, while also producing a significant amount of energetic ultraviolet (UV) light. This combination of soft X-rays and strong UV radiation is a unique spectral pattern that had not been observed before. The researchers identified these sources by looking at images taken at the lowest X-ray energies, where the objects appeared, but vanished in higher-energy images—showing that they emit far more soft X-rays than hard X-rays. The data used for this analysis was publicly available in the Chandra archive, including some observations that were several years old. The six galaxies studied include two spiral galaxies—M31, also known as the Andromeda galaxy, and M101, called the Pinwheel galaxy—and four elliptical galaxies. The hypersoft sources were found in both regions where new stars are forming and in areas dominated by older stars. This suggests that these sources are not confined to a specific galactic environment. Additionally, they emit large amounts of energetic UV radiation, a characteristic that does not match any known class of astronomical objects. The research, led by Mustafa Muhibullah from the University of Alabama, was published in the journal Nature Astronomy on September 9, 2026. The team noted that these objects have never been observed to behave in this way before. The extreme UV radiation they emit is hard to observe directly because it is absorbed by neutral hydrogen and helium in interstellar space, creating what NASA describes as an "almost impenetrable barrier." Rosanne Di Stefano, a coauthor from the Center for Astrophysics at Harvard and the Smithsonian, explained that by reexamining the Chandra archive, the team was able to uncover a previously unknown class of cosmic objects. The researchers proposed possible explanations, such as black holes, neutron stars, or white dwarfs pulling matter from a companion star in a binary system. However, the specific ratio of X-ray to UV radiation remains a mystery. This discovery could provide important insights into type Ia supernovae, which are critical for measuring distances in the universe, and into the ionization of interstellar gas in distant galaxies. The researchers emphasized that this finding was made by applying a new analytical approach to existing data, rather than by using a new instrument or technology. Their work highlights the value of re-examining old data with fresh perspectives to uncover previously hidden cosmic phenomena.