Astronomers have found evidence that two massive stars from the same binary system ended their lives as supernovae. The two explosions would have left neighboring remnants in the constellation Gemini, about 6,000 light-years from Earth.
The first remnant is the Jellyfish Nebula, also known as IC 443. This bright structure corresponds to the expanding debris of a stellar explosion. Researchers have studied it for a long time at different wavelengths, particularly in the radio, infrared, ultraviolet, and X-ray domains.
The supernova remnant IC 443, on the right, interacts with its older neighbor G189.6+3.3 in the same molecular cloud. X-rays, gamma rays, ultraviolet, and visible light reveal their shock waves.
Credit: NASA Goddard Space Flight Center and M. Michailidis et al. 2026. Radio, infrared, optical, ultraviolet, X-ray, and gamma-ray data.
The second remnant, designated G189.6+3.3, is much fainter. It appears more clearly in radio and X-ray observations. Data accumulated over more than 16 years by the Fermi gamma-ray space telescope has helped refine its characteristics.
The two stars would have been very massive and tens of thousands of times more luminous than the Sun. They may have possessed more than fifteen times its mass. In a binary system, their gravitational interactions and matter exchanges strongly modify their evolution.
The star that originated G189.6+3.3 would have exploded first, between 20,000 and 110,000 years before the one that formed the Jellyfish Nebula. The supernovae would therefore be separated by a very short interval on the scale of a star's life.
A first explosion can also alter the motion of the surviving star. The shock wave and sudden loss of mass can destabilize the system, and the companion star continues to evolve until its own explosion.
This discovery would provide a rare means of studying the fate of two massive stars born together.