This Is the Start of a Supernova

Astronomers have managed an unprecedented look at the early stage of a supernova, a massive star's explosion and death, finding that it doesn't resemble the perfect sphere many expected. When a massive star in the galaxy NGC 3621, 22 million light-years away, exploded in April 2024, scientists using the Very Large Telescope in Chile were able to record the event about 26 hours after its detection and 29 hours after "material from inside the star first broke through the stellar surface," per France 24. Using a technique called spectropolarimetry to analyze the light from the explosion, astronomers captured a glimpse of the supernova's "breakout" shape, according to a study published in Science Advances.

The captured data is translated into an artist's rendering, revealing that, rather than exploding evenly in all directions, the dying star's shock wave was elongated along a single axis, resembling an olive more than a ball, per Live Science. This was captured just in time, the outlet notes, as the shape changed within a day of the VLT's first observation. As the blast expanded, the hydrogen-rich outer layers of the star became visible around the 10-day mark, and those layers were found to be aligned with the same axis as the initial shock. "Scientifically this is very important, because the intrinsic shape of the shock breakout tells us a lot of how it was triggered at the heart of the star in the first place," study co-author Yi Yang tells Science News.