A Star’s Naked Death Shines Light on the Origins of Matter
Astronomers have caught a dying star in the act of baring its deepest layers before erupting in a fireball—a discovery that is rewriting what scientists know about the life and death of massive suns. The explosion, dubbed SN2021yfj, was first detected in September 2021, but this week researchers led by Northwestern University and Israel’s Weizmann Institute of Science announced in Nature that it represents an entirely new kind of supernova—one that exposes the star’s hidden core.
“This is the first time we have seen a star that was essentially stripped to the bone,” said lead author Steve Schulze, a former Weizmann researcher now at Northwestern University. “It shows us how stars are structured and proves they can be stripped all the way down and still produce a brilliant explosion visible from very far away.”
Ordinarily, when giant stars explode, telescopes pick up only the outermost shells of light elements like hydrogen and helium. This time, the blast lit up with heavy elements—silicon, sulfur, argon—that are normally buried deep inside. Israeli astrophysicist Avishay Gal-Yam, who heads Weizmann’s experimental astrophysics group, said, “Once we identified the spectral signatures of silicon, sulfur, and argon, it was clear this was a major step forward: Peering into the depths of a giant star helps us understand where the heavy elements come from.”
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The study brought together researchers from the US, Israel, France, Italy, China, Sweden, Ireland, the UK, Japan, and Serbia. Israeli scientists, including Gal-Yam and Dr. Ofer Yaron, played a central role in decoding the light spectrum, while colleagues in California secured the crucial observations after telescopes worldwide were hampered by clouds or scheduling gaps.
Massive stars, weighing 10 to 100 times more than our Sun, are built like onions: light gases outside, heavier elements inside, with an iron core at the center. SN2021yfj revealed that such stars can shed nearly all their outer shells before collapse, leaving the core naked at the moment of detonation.
For scientists, the discovery is more than an astrophysical curiosity. It helps explain how the universe produces the elements that shape our lives: the silicon in Earth’s rocks, the sulfur in its seas, the calcium in our bones, the iron in our blood. “Every atom in our bodies and in the world around us was created somewhere in the universe,” Gal-Yam said. “Tracing its origin is incredibly difficult, but now we know the inner layers of giant stars are key production sites.”
SN2021yfj burned out long ago, its light traveling 2.2 billion years to reach Earth. But in its death, the star offered humanity a rare gift: a glimpse into the universe’s forge, where matter itself is made.
