This Is What a Star Looks Like Just 26 Hours After It Explodes

Astronomers have captured a first-of-its-kind image of a massive dying star.

Just 26 hours after the supernova SN 2024ggi was first detected in April 2024, the European Southern Observatory (ESO) pointed its Very Large Telescope (VLT) in Chile at the dramatic astronomical event. Supernovas are the explosive deaths of stars, and ESO’s VLT managed to capture this one in its earliest moments—just as the blast was rupturing through the star’s surface. This achievement reveals, for the first time, the supernova’s shape at its earliest, ephemeral stage.

This is great news for researchers because “the geometry of a supernova explosion provides fundamental information on stellar evolution and the physical processes leading to these cosmic fireworks,†Yi Yang, an astronomer at Tsinghua University and co-author of a study published today in Science Advances, explained in an ESO statement.

An explosive mystery

As iconic as supernovas are, researchers continue to debate exactly how massive stars—stars with over eight times the mass of the sun—go supernova. When a massive star runs out of fuel, its core collapses and its surrounding shells of mass fall inward before bouncing off in a rebound shock that spreads outward and releases a huge amount of energy when it breaks through the star’s surface. That’s when the supernova becomes bright and observable.

“The death of massive stars is triggered by an infall-induced bounce shock that disrupts the star. How such a shock is launched and propagates through the star is a decades-long puzzle,†Yang and his colleagues wrote in the study. At just 22 million light-years away, in the galaxy NGC 3621, supernova SN 2024ggi is not far by astronomical standards. Before exploding, it was a red supergiant star with 12 to 15 times the mass of the Sun and a radius 500 times larger.

The team was able to capture the short-lived “breakout†shape—before the eruption interacts with surrounding material—for the very first time with a technique called spectropolarimetry. The technique “delivers information about the geometry of the explosion that other types of observation cannot provide,†explained Lifan Wang, co-author of the study and an astronomer at Texas A&M University.

If you’re imagining a detailed photograph of a colorful explosion, that’s not what we’re talking about here (the feature image up top is an artist’s interpretation based on the new data). The supernova appears as a single point, but the researchers were able to reconstruct its geometry from the polarization of its light. Simply put, polarization is a property of light particles that, in certain cases, allows researchers to infer the shape of the light-emitting star or supernova.

Olive-shaped

The team found that the initial blast was olive-shaped, and as the material propagated outward and hit matter around the star, it flattened but maintained the same axis of symmetry. “These findings suggest a common physical mechanism that drives the explosion of many massive stars, which manifests a well-defined axial symmetry and acts on large scales,†said Yang.

Thanks to these results, astronomers can now rule out a number of the current supernova models and improve others, honing in on the exact nature of these powerful explosions.