Overview
- The research team published a peer-reviewed paper in Nature Communications on July 21, 2026, reporting that G189.6+3.3 is a distinct supernova remnant located next to the well-known IC 443 (the Jellyfish Nebula).
- The identification rests on stacked gamma-ray data from more than 16 years of NASA Fermi LAT observations combined with X-ray detections from ROSAT and SRG/eROSITA and other wavelength maps that trace a shell of hot plasma around G189.6+3.3.
- Spectral maps show different gamma-ray signatures across G189.6+3.3: proton-linked emission where the remnant hits the dense S249 H II cloud and electron-driven emission in more diffuse regions, linking both remnants to the same interstellar cloud.
- The authors estimate the older remnant (G189.6+3.3) exploded between about 20,000 and 110,000 years ago while IC 443 formed roughly 8,000–9,000 years ago, their explosion centers now 30–50 light-years apart, and they calculate about a 1 in 1,000 chance that the close alignment is random.
- If confirmed as a disrupted massive binary, the system would give scientists a rare empirical tool to test models of binary evolution, measure explosion timing and natal kicks, and study how paired supernovas accelerate cosmic rays, and the team plans targeted searches for more such pairs.