84 Objects Are Hiding in Nearby Galaxies. They Vanish When You Look Too Hard.

The objects show up in Chandra's lowest-energy X-ray images and then simply disappear in higher-energy ones. Not because they're faint. Because they give off far more low-energy X-rays than high-energy ones, and because low-energy X-rays border energetic ultraviolet radiation on the electromagnetic spectrum, they are pouring out enormous amounts of ultraviolet light as well. No known class of cosmic object does this. There are 84 of them.

Searching Chandra Observatory archival images across six galaxies, scientists found a total of 84 such objects and have dubbed them hypersoft X-ray sources. Nobody knows yet what class of object produces this combination. A companion star feeding material onto a black hole, neutron star or white dwarf is a familiar enough arrangement, and the team suspects one of those three is at the center of this too, but nothing that setup normally produces looks like this. The combination of bright ultraviolet output and hypersoft X-rays has not been seen in such systems before.

Part of why these went unnoticed for so long borders on poetic. Their low-energy X-ray signal sits right at the edge of what instruments like Chandra can register, and the ultraviolet output runs straight into an interstellar wall — helium and hydrogen gas threading between the stars absorbs it nearly completely before it reaches any telescope. The universe had been hiding these things behind two separate curtains simultaneously.

The discovery may end up answering two separate open questions in astrophysics at once. One involves where galaxies get the ionizing energy needed to strip electrons from interstellar gas. Hot massive stars cannot fully supply the extreme-ultraviolet photons required; a 2025 paper proposed that cool, luminous sources like these could provide the missing ones.

Both older stellar regions and active star-forming regions contained the new objects. Nobody knows yet why.

Read the full story at NASA Science, September 9, 2026

Hot Take: Don't tell Superman, that X-ray vision has settings where the interesting stuff disappears.