First evidence of binary supernovae discovered in Milky Way

Scientists have found the first evidence of two massive stars in a binary system that both exploded as supernovae, leaving behind the Jellyfish Nebula (IC 443) and a fainter companion G189.6+3.3. The discovery, published in Nature Communications and based on 16 years of data from NASA's Fermi Gamma-ray Space Telescope, resolves a long-standing mystery about the origins of these nearby nebulas.

What happened

Both remnants lie about 6,000 light-years away in the constellation Gemini. The star that created the Jellyfish Nebula was 15–25 times the Sun's mass, while its companion was at least 20 solar masses. The explosions occurred within a relatively short period, leaving behind neutron stars. The researchers used gamma-ray observations to separate the two sources, confirming G189.6+3.3 is an independent supernova remnant accelerating particles.

Significance

• First binary supernova pair: No such pair had been confirmed before, despite most massive stars forming in binaries Source: CNA.
• Caution on certainty: Lead author Miltiadis Michailidis calls it a "candidate" but says it is "very unlikely" to be a chance alignment Source: Gizmodo.
• Insight into stellar evolution: This system offers a rare chance to reconstruct the complete evolutionary history of a massive binary, from birth to double supernova Source: CNA.