18 Years Later: A Supernova Lights Up the Radio ⚡ экспресс
For the first time, radio emission has been recorded from the Type II supernova SN 2007it in the galaxy NGC 5530 (distance 12.2 Mpc). The observations were carried out using the Australia Telescope Compact Array (ATCA) more than 18 years after the explosion, as part of the RISE program, which aims to detect late-time interaction of supernova remnants with dense circumstellar material. On April 8, 2026, the source was detected at frequencies of 5.5 GHz (flux density 3.30±0.13 mJy) and 9.0 GHz (3.54±0.24 mJy). The lack of detection in archival ASKAP data at 0.88 GHz from January 11, 2026, suggests either rapidly increasing emission or significant internal absorption at low frequencies. Prospects for observations at other wavelengths are discussed, and coordinated campaigns in the radio, optical, X-ray, and gamma-ray bands are proposed.
A supernova explosion is the death of a massive star, leaving behind a gas cloud. If there's plenty of hydrogen around, the shock wave spreads like an echo from a distant gunshot. For supernova SN 2007it, that echo arrived 18 years later: the wave finally slammed into a dense clump of material ejected by the star before the explosion, triggering radio emission. The ATCA telescope caught the radio signal. Brightness measurements showed the emission is rapidly brightening.
The discovery explains how stars shed mass before the final blast, scattering raw materials for new worlds across the cosmos. This is the first time a supernova has given a radio echo with such a delay.
🎯 The signal was so unexpected that it was almost dismissed as radio interference, and only a data check confirmed it: a supernova, finally speaking up after 18 years.