Chandra X-ray data reveals hidden compact companion driving 27-year supernova impostor cycle
NASA’s Chandra X-ray Observatory has identified the mechanism behind AT 2016blu, a star in galaxy NGC 4559 that has mimicked a supernova 27 times since 2012. The star, a luminous blue variable, is being stripped of material by an unseen companion, likely a black hole or neutron star, every 113 days. This interaction generates intense X-rays that heat surrounding gas, creating the bright optical flashes previously mistaken for stellar explosions. The findings, published in The Astrophysical Journal, mark the first X-ray detection of a supernova impostor with a compact companion.