Astronomers have found visual evidence of a star exploding twice, a phenomenon called a double detonation. Using the European Southern Observatory's Very Large Telescope (VLT), they observed supernova remnant SNR 0509-67.5, revealing two concentric calcium shells. This confirms a theoretical model of Type Ia supernovae where a white dwarf explodes before reaching critical mass. The discovery, published in Nature Astronomy, sheds light on the mechanism behind these crucial stellar explosions, which play a key role in understanding the universe's expansion and the origin of elements like iron.

Prepared by Olivia Bennett and reviewed by editorial team.