JWST Spots Hidden Red Supergiant Just Before It Exploded, Solving Cosmic Mystery
Webb Telescope's infrared vision pierces through cosmic dust to reveal a massive star's final moments, bridging the gap between theory and observation for the first time.
October 9, 2025 - In a groundbreaking discovery that solves a long-standing cosmic puzzle, NASA's James Webb Space Telescope has captured the clearest view ever of a dying star just before its dramatic explosion. Astronomers from Northwestern University have identified a massive red supergiant star hidden beneath layers of dust that subsequently exploded as a supernova - marking JWST's first confirmed detection of a supernova's progenitor star.
The findings, published in The Astrophysical Journal Letters, explain why astronomers have rarely observed red supergiants exploding despite theoretical models predicting they should account for most core-collapse supernovae. The answer: these enormous stars are often shrouded in thick dust clouds that visible light cannot penetrate.
Solving the Missing Star Mystery
The international team, led by Northwestern's Charlie Kilpatrick, first detected the supernova SN2025pht on June 29, 2025, in the spiral galaxy NGC 1637, located about 40 million light-years from Earth. By combining archival observations from the Hubble Space Telescope with new data from JWST, researchers pinpointed the progenitor star that had been invisible to previous telescopes.
"For multiple decades, we have been trying to determine exactly what the explosions of red supergiant stars look like," said Kilpatrick, a research assistant professor at Northwestern's Center for Interdisciplinary Exploration and Research in Astrophysics. "Only now, with JWST, do we finally have the quality of data and infrared observations that allow us to say precisely the exact type of red supergiant that exploded and what its immediate environment looked like."
The Reddest, Dustiest Supergiant
The progenitor star immediately stood out as both brilliant and intensely red. Although it radiated approximately 100,000 times more light than the Sun, much of its glow was hidden by surrounding dust. The dust layer was so dense that it made the star appear over 100 times dimmer in visible light than it would otherwise appear.
"It's the reddest, dustiest red supergiant that we've seen explode as a supernova," said study co-author Aswin Suresh, a graduate student in physics and astronomy at Northwestern. "SN2025pht is surprising because it appeared much redder than almost any other red supergiant we've seen explode as a supernova."
The discovery supports the hypothesis that the most massive aging stars might also be the dustiest, with thick cloaks of dust dimming their light to the point of near undetectability by conventional telescopes.
Unexpected Carbon-Rich Dust
Adding to the surprise, the dust surrounding the star had an unusual composition. While red supergiants typically produce oxygen-rich, silicate dust, this star's dust appeared rich with carbon. This suggests that powerful convection in the star's final years may have dredged up carbon from deep inside, enriching its surface and altering the type of dust it produced.
"The infrared wavelengths of our observations overlap with an important silicate dust feature that's characteristic of some red supergiant spectra," Kilpatrick explained. "This tells us that the wind was very rich in carbon and less rich in oxygen, which also was somewhat surprising for a red supergiant of this mass."
A New Era for Stellar Astronomy
This discovery marks the beginning of a new era for studying exploding stars. JWST's ability to capture light across the near- and mid-infrared spectrum enables astronomers to see through obscuring dust and finally witness what previous telescopes could not.
The team is now searching for similar red supergiants that may explode as supernovae in the future. Upcoming observations by NASA's Nancy Grace Roman Space Telescope, with its resolution, sensitivity and infrared wavelength coverage, may help identify more of these hidden giants and potentially witness their variability as they near the end of their lives.
"With the launch of JWST and upcoming Roman launch, this is an exciting time to study massive stars and supernova progenitors," Kilpatrick said. "The quality of data and new findings we will make will exceed anything observed in the past 30 years."
*The study, "The Type II SN 2025pht in NGC 1637: A red supergiant with carbon-rich circumstellar dust as the first JWST detection of a supernova progenitor star," was supported by the National Science Foundation.*