On 21 March 2026 the Einstein Probe satellite caught a brief X-ray flash, catalogued as EP260321a, from a galaxy roughly 500 million light-years away. Astronomers interpret it as a shock breakout: the instant a shock wave from a star's collapsing interior bursts through its surface, releasing the first light of a supernova. Only one other X-ray shock breakout has been confidently identified in the past two decades, making the event a rare chance to watch a stellar death from its opening moments.
LMU astrophysicist Daniel Grün led follow-up observations with the university's 2.1-metre Fraunhofer Telescope on Mount Wendelstein and its share of the Hobby-Eberly Telescope in Texas, capturing near-nightly images as the explosion, supernova SN 2026gzf, evolved. The spectra revealed a progenitor star formed from nearly pristine gas, with only about 15 per cent of the Sun's metal content, and newly forged metals were already streaming outwards four days after breakout.
The puzzle is what did not appear. SN 2026gzf is a broad-lined Type Ic supernova, a class normally associated with relativistic jets and gamma-ray bursts, yet searches with the Chandra X-ray Observatory and the Very Large Array found no jet and no afterglow. The team's favoured explanation, published in The Astrophysical Journal Letters, is a jet launched but choked inside the star, evidence that massive stars die through a wider range of pathways than supposed.