NASA's Chandra finds a brand-new class of X-ray objects

Astronomers combing through old, public data from NASA's Chandra X-ray Observatory found something that doesn't fit any known category. In six galaxies, they spotted 84 objects giving off unusually weak, low-energy X-rays paired with strangely intense ultraviolet light. NASA is calling them "hypersoft X-ray sources." Nobody has described anything quite like them before.

The name comes from a mismatch. Weak X-rays don't usually show up next to such bright ultraviolet light. A team led by researcher M. Muhibullah, at the University of Alabama, made the find. They used data anyone can download from Chandra's public archive. No new observing time was needed. The discovery might help answer two long-standing puzzles. One: how a certain type of exploding star, called a Type Ia supernova, actually forms. Two: what lights up the faint gas drifting between a galaxy's stars. That's promising, but it's early. Nobody has confirmed what these 84 objects actually are. So far, they just don't match anything in the astronomy textbooks.

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Will more of these turn up once astronomers know to look for them? That's the real test. Chandra's archive holds decades of data on thousands of galaxies. This team only checked six of them. If hypersoft sources turn out to be everywhere, that tells us something big. It means a whole category of the universe has been hiding in plain sight.