NASA's Chandra X-ray Observatory has helped uncover a likely explanation for a so-called "supernova impostor" in galaxy NGC 4559.
What looked like a massive star explosion back in 2012 was actually a bright, unstable star slowly losing its material to an invisible black hole or neutron star nearby.
That explains why it kept lighting up every few months, definitely not your average supernova.
Chandra shows accretion heats glowing cloud
Chandra's latest observations from March 2026 showed strong X-rays whenever the compact object pulled in more material, which heated the surrounding cloud of material, which then glowed like an explosion.
This helps scientists understand how these "impostors" work and how they might be linked to ultraluminous X-ray sources (ULXs).
The findings open up new questions about what's really going on when we spot sudden bright flashes in deep space.