About 40 million years ago, a star exploded in a nearby galaxy, sending light hurtling through space. This light finally arrived on Earth on June 29, 2025. Thanks to the All-Sky Automated Survey for Supernovae, astronomers caught sight of the new supernova, named 2025pht. They quickly shifted their focus to learn more about this cosmic event.
Rather than just studying the supernova itself, one team decided to dig into past images to find the star that had exploded. They succeeded, using photos from NASA’s James Webb Space Telescope of galaxy NGC 1637. They spotted a red supergiant star right where the supernova now blazes. This marked the first time Webb has detected a progenitor star before an explosion, as highlighted in the Astrophysical Journal Letters.
Lead author Charlie Kilpatrick from Northwestern University expressed excitement over this discovery. He said, “We’ve been waiting for this to happen – for a supernova to explode in a galaxy that Webb had already observed.” The team combined data from both Hubble and Webb to characterize this star in unprecedented detail.
The matched images showed the star’s unique color. Using Webb’s Mid-Infrared Instrument and Near-Infrared Camera, the scientists noted how red the star appeared, which hinted at a thick dust layer surrounding it. Graduate student and co-author Aswin Suresh remarked, “It’s the reddest, most dusty red supergiant that we’ve seen explode.”
This discovery can help address a longstanding mystery in astronomy regarding the “missing” red supergiants. While astronomers expect that the most massive stars erupting as supernovae should be bright and easy to find, they haven’t always been observed. One reason could be that these massive stars are often cloaked in dust, which dims their light. Kilpatrick shared, “This finding supports the idea that the most massive supergiants are hidden due to their dust.”
Interestingly, the researchers discovered something unexpected about the dust itself. Models indicated that it is rich in carbon, which was a surprise. It suggests that this carbon might have been pushed from the star’s interior just before it exploded. As Suresh noted, “Mid-infrared observations were crucial to figuring out the dust composition.”
Looking ahead, the team plans to locate similar red supergiants that could become supernovae in the future. They anticipate that NASA’s upcoming Nancy Grace Roman Space Telescope will be vital in this search. Roman’s advanced capabilities in resolution and infrared observation may allow scientists to see these stars and their behavior as they get close to their explosive ends.
The James Webb Space Telescope is a cutting-edge observatory and plays a big role in advancing our understanding of the universe. It helps us explore our solar system, distant exoplanets, and unravel cosmic mysteries. Webb is a collaborative effort led by NASA, with contributions from the ESA and CSA.
To discover more about the Webb telescope’s exciting findings, visit science.nasa.gov/webb.
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Astrophysics, Goddard Space Flight Center, James Webb Space Telescope (JWST), Science & Research, Spiral Galaxies, Stars, Supernovae, The Universe
