Astronomers Find 84 Hidden X-Ray Sources
A team reexamining NASA Chandra archival data uncovered previously unknown low-energy X-ray sources across six galaxies.
Updated on Nov. 8, 2026 in Space
Astronomers led by Mustafa Muhibullah at the University of Alabama identified 84 previously unknown low-energy X-ray sources in archival data from NASA's Chandra X-ray Observatory. The sources were found across six galaxies, including the Andromeda galaxy, and were previously overlooked because their faint soft X-rays are absorbed by surrounding gas.
Why it matters
Low-energy X-rays are often discarded in analysis because detectors respond poorly at that energy, meaning a population of sources may have been systematically missed. The discovery may change what scientists understand about the universe, though its implications remain under study.
The team's analysis covered Chandra archival observations of the Andromeda galaxy and five other galaxies, with 84 sources identified in faint images that disappear in stronger ones. The sources' ultraviolet emission and effects on nearby stars have not yet been confirmed by follow-up study.
The players
NASA Chandra X-ray Observatory
Chandra is one of NASA's Great Observatories, launched in 1999 to study X-rays from high-energy regions of the universe that cannot be observed from Earth's surface.
Mustafa Muhibullah
Muhibullah is the lead researcher of the team at the University of Alabama that reexamined Chandra archival data to find the 84 sources.
The details
The researchers searched NASA Chandra's public archive for points of light that appeared in the faintest images and vanished in stronger ones. The sources sit in regions of both new star formation and older stars, and the hydrogen and helium gas surrounding them absorbs their low-energy X-ray light, which is why they went unseen.
Timeline
23 July 1999: NASA's Chandra X-ray Observatory launched aboard the Space Shuttle Columbia.
8 November 2026: Article reporting the 84 X-ray source discovery was published.
The Big Picture
The finding extends the value of NASA's Chandra X-ray Observatory, a Great Observatory launched in 1999, by showing its public archive still holds undiscovered sources in soft X-rays that routine analysis often discards. It suggests that long-standing assumptions about which X-ray sources astronomers can detect may need revisiting.
The discovery could eventually inform how astronomers filter and interpret X-ray data from distant galaxies, potentially changing which objects are counted in future surveys. Any practical or scientific consequences depend on follow-up studies of the sources' ultraviolet emission.
The takeaway
Archival data can still yield major discoveries when researchers revisit faint signals that were previously dismissed as unreliable. Readers interested in space science can follow how new analysis techniques reshape long-held assumptions about the universe.
Further reading
Explore more Space coverage to see how astronomers are using archival telescope data to revisit the cosmos.
