A composite optical and X-ray image of NGC 4559. The purple dots are X-ray sources; AT 2016blu is highlighted in the square box (Image credit: X-ray: NASA/CXC/University of Virginia/M. Aghakhanloo et al.; Optical: SDSS; Image Processing: NASA/CXC/SAO/P. Edmonds.)

A cosmic imposter that has faked being a supernova 27 times and counting is actually a hot, luminous, and decidedly unstable star that is being fed on by a vampiric black hole or neutron star, NASA’s Chandra X-ray Observatory has discovered.

When a massive star reaches the end of the road and runs out of nuclear fuel to power fusion reactions in its core, the star is destroyed in a supernova explosion.…