We just saw the exact moment a star exploded for the first time ever. Astronomers have achieved a rare feat: imaging the exact moment a massive star detonated—and the explosion was anything but spherical. SN 2024ggi, a supernova located 22 million light-years away in the spiral galaxy NGC 3621,... was detected a mere 26 hours after ignition. This extraordinarily early discovery allowed researchers to train the European Southern Observatory’s Very Large Telescope in Chile on the event while it was still in its infancy. Using the technique of spectropolarimetry—which analyzes the polarization of light to reveal geometric structure—the team uncovered a surprising truth: the expanding shockwave was distinctly aspherical, elongated into an “olive” or prolate shape along one primary axis. This asymmetry means the catastrophic rebound following the star’s core collapse did not propagate uniformly in all directions, directly contradicting the long-standing assumption that the deepest layers of a core-collapse supernova explode spherically. The progenitor was a red supergiant 12–15 times more massive than the Sun that had exhausted its nuclear fuel, triggering gravitational collapse of its iron core. In most supernovae, the initial shape of this breakout is quickly obscured as the blast wave slams into the star’s outer envelope. Here, however, astronomers captured polarized light signatures of the still-unobscured ejecta, freezing the explosion’s geometry in time. The discovery carries far-reaching consequences. It strongly suggests that asymmetry is common, if not universal, in the earliest phases of massive-star deaths. Current theoretical models, which often assume spherical symmetry at the core, will need significant revision. Moreover, these distorted explosions could help explain observed peculiarities in supernova remnants, the production of gamma-ray bursts, and the kicking of neutron stars and black holes to high speeds at birth. By catching a star in the act of dying asymmetrically, SN 2024ggi has given us a vivid glimpse into the violent, chaotic physics that govern the final heartbeat of the universe’s most massive stars. [🎞️ Artist’s animation of a supernova explosion] [Unique shape of star’s explosion revealed just a day after detection. ESO, 2025]show more

Massimo

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