NASA's Chandra X-ray Observatory has uncovered the likely cause of mysterious, repeating outbursts from a massive star located about 30 million light-years from Earth.
The star, known as AT 2016blu, is at least 33 times the mass of our sun and has been erupting roughly every 113 days for more than a decade. New X-ray observations suggest a previously hidden companion — either a black hole or neutron star — is stealing material from the unstable star as the two orbit one another.
Located in the spiral galaxy NGC 4559, the star's outbursts can resemble supernova explosions, but it survives each eruption. Chandra observations from March 2026 revealed that AT 2016blu had become at least 100 times brighter in X-rays compared with observations taken before the eruptions began.
The discovery could help astronomers understand violent stellar outbursts and the behavior of massive stars approaching the ends of their lives.
Credit: NASA/CXC/A. Hobart
