Researchers rapidly mobilized the Very Large Telescope after the April 10, 2024 detection of supernova SN 2024ggi in a nearby galaxy. Using spectropolarimetry and fast international coordination, the team led by Yi Yang captured the explosion’s breakout phase and found the initial flash was elongated — an "olive-shaped" (prolate) geometry — that flattened as the ejecta expanded. The progenitor was a red supergiant of about 12–15 solar masses, and the findings, published in Science Advances, provide the first direct observational constraints on the early shape of a massive-star supernova.
Astronomers Capture the First Moments of a Nearby Supernova — An Olive-Shaped Blast Reveals New Clues
Researchers rapidly mobilized the Very Large Telescope after the April 10, 2024 detection of supernova SN 2024ggi in a nearby galaxy. Using spectropolarimetry and fast international coordination, the team led by Yi Yang captured the explosion’s breakout phase and found the initial flash was elongated — an "olive-shaped" (prolate) geometry — that flattened as the ejecta expanded. The progenitor was a red supergiant of about 12–15 solar masses, and the findings, published in Science Advances, provide the first direct observational constraints on the early shape of a massive-star supernova.
08:53 AM, 11/13/2025Science
A race against time in the Atacama
A cross-agency scramble to reconfigure telescopes on a Chilean mountaintop reads like a thriller, but the urgency was scientific: the explosive death of a massive star and a rapidly closing window to record its earliest light.
Immediate response to SN 2024ggi
On April 10, 2024, researchers identified supernova SN 2024ggi in a nearby galaxy. Yi Yang, an assistant professor at Tsinghua University, quickly requested access to the European Southern Observatory’s Very Large Telescope (VLT) in Chile to capture the event during its first instants. Because the breakout phase of a core-collapse supernova evolves in hours to days, rapid coordination was essential.
Why the first moments matter
Massive stars develop layered shells of progressively heavier fusion products around their cores. When nuclear fuel is exhausted, those shells collapse inward, rebound and launch shock waves outward. The initial "breakout phase" of that shock carries direct information about the explosion geometry, the progenitor structure and the physical mechanisms that trigger the blast.
Measuring shape with spectropolarimetry
In a paper published in Science Advances, Yang and colleagues used spectropolarimetry — a technique that infers the three-dimensional geometry of an explosion from the polarization of its light — to probe SN 2024ggi’s earliest flash. Their analysis indicates the initial emission was not spherical: it was elongated (a prolate or "olive-shaped" geometry) and then became more flattened as the ejecta expanded, while retaining a clear axis of symmetry.
"The geometry of a supernova explosion provides fundamental information on stellar evolution and the physical processes leading to these cosmic fireworks," Yang said.
Implications for stellar evolution and theory
These direct observations provide a crucial constraint for models of core-collapse supernovae. The detected asphericity — an initially prolate shape that relaxes yet keeps an axis — favors explosion scenarios in which asymmetric mechanisms (for example, jet-like flows or uneven neutrino-driven convection) play a significant role. The progenitor in this case was a red supergiant with an estimated mass of roughly 12–15 solar masses.
Co-author Ferdinando Patat added that the result demonstrates how curiosity, rapid coordination and international collaboration can unlock deep physical insights about the universe.
Lead image: ESO/L. Calçada
Note on distance: The original report listed the object as "22 light-years" away; that value is implausibly close for an extragalactic supernova and likely a typographical error. Contemporary reports and the context of the discovery indicate the supernova is in a nearby galaxy at a distance on the order of tens of millions of light-years. We have used "nearby galaxy" rather than the erroneous literal value.