Using NASA’s Chandra X-ray Observatory, scientists have identified a previously unknown class of objects: «hypersoft X-ray sources». Researchers found 84 such objects in six different galaxies (including the spirals M31 and M101) by sifting through publicly available Chandra archive data. These sources emit unusually low-energy X-rays but also produce intense levels of ultraviolet radiation. The team suggests they likely involve compact objects (black holes, neutron stars, or white dwarfs) pulling material from a companion star. What’s intriguing is that this combination of low-energy X-rays and strong UV emission hasn’t been observed in such systems before. The discovery could help solve two astrophysical puzzles: it might explain a significant source of energetic ultraviolet radiation in galaxies (which affects star formation) and provide clues about what strips electrons from interstellar gas. The reason these objects eluded detection for so long is twofold: low-energy X-rays are hard for telescopes to pick up, and the strong UV radiation gets absorbed by interstellar gas (hydrogen and helium), acting as a nearly impenetrable barrier.
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