Overview
- Researchers announced in mid‑June 2026 that careful analysis of 16 years of Fermi Large Area Telescope data revealed gamma‑ray emission from a faint remnant, G189.6+3.3, previously hidden by the bright Jellyfish Nebula (IC 443).
- The team found gamma rays in the fainter remnant that match the signature of protons accelerated by a supernova shock, showing both remnants act as particle accelerators interacting with the same gas.
- Multiwavelength images show a gas filament linking the two objects and evidence they both meet the same molecular cloud, which supports a common distance and physical association.
- Age estimates place IC 443 at roughly 8,000–9,000 years and G189.6+3.3 between about 20,000 and 110,000 years, consistent with two explosions separated by up to ~100,000 years in a massive binary system.
- Simulations of more than a million massive binaries and a statistical test that gives under a 1 percent chance of a random alignment strengthen the conclusion, and follow‑up observations and modeling have been flagged to refine ages, distances and the dynamical history.