NASA, ESA, CSA, STScI, Charles Kilpatrick (Northwestern), Aswin Suresh (Northwestern)
A team of astronomers led by Northwestern University has captured the most detailed glimpse yet of a doomed star before it exploded.
Using NASA’s James Webb Space Telescope, the international team identified, for the first time, the source star of a supernovaor progenitor, at mid-infrared wavelengths.
These observations – combined with archival images from the Hubble Space Telescope – revealed that the explosion originated from a huge red supergiant star, surrounded by an unexpected blanket of dust.
The discovery could help solve the decades-old mystery of why massive red supergiants rarely explode.
Indeed, theoretical models predict that red supergiants should make up the majority of core-collapse supernovae.
The new study shows that these stars do explode, but they are simply hidden, inside thick clouds of dust.
With Webb’s new capabilities, astronomers can finally penetrate the dust to detect these phenomena, closing the gap between theory and observation.
The was published in The Astrophysical Journal Letters. It marks the first detection of a supernova progenitor by the James Webb Space Telescope.
“For several decades we have been trying to determine exactly what exploding red supergiant stars look like,” Charlie Kilpatrick, who led the study.
“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 was like. We’ve been waiting for this to happen – for a supernova to explode in a galaxy that JWST has already observed. We’ve combined the Hubble and JWST data to fully characterize this star for the first time.” time.”
An expert on the life and death of massive stars, Kilpatrick is a research assistant professor at Northwestern University’s Center for Interdisciplinary Exploration and Research in Astrophysics. Aswin Suresh, a physics and astronomy student, also at the same educational institution, is one of the main co-authors of the scientific article.
The reddest and dustiest parent ever observed
Using ASAS-SN (All-Sky Automated Survey of Supernovae), astronomers first detected the supernova, designated SN 2025pht, on June 29, 2025. Its light had traveled from a nearby galaxy called NGC 1637, located 40 million light years from Earth.
By comparing Hubble and Webb images of NGC 1637 before and after the star’s explosion, Kilpatrick, Suresh and their collaborators found SN 2025pht’s progenitor star. It immediately caught my attention – extremely bright and incredibly red. Although the star shined about 100,000 times brighter than our Sun, the dust circundante obscurecia much of that light. The veil of dust was so thick, in fact, that the star appeared more than 100 times fainter in visible light than it would have without the dust. Because the dust blocked the shorter, bluer wavelengths of light, the star also appeared surprisingly red.
“It’s the reddest and dustiest red supergiant we’ve ever seen explode as a supernova“, disse Suresh.
Massive stars in the final stages of their lives, red supergiants are among the largest stars in the Universe. When their cores collapse, they explode as Type II supernovae, leaving behind either a neutron star or a black hole. The best-known example of a red supergiant is , the bright red star on the shoulder of the constellation Orion.
“SN 2025pht é surprising because it appeared much redder than almost every other red supergiant we’ve seen explode as a supernova,” Kilpatrick added. “This tells us that previous explosions may have been much more luminous than we thought, because we didn’t have the same quality of infrared data that JWST can now provide.”
Clues hidden in the dust
The dust avalanche may help explain why astronomers have had difficulty finding progenitor red supergiants. The most massive stars that explode as supernovae are the brightest and most luminous objects in the sky. Therefore, in theory, they should be easy to detect before they explode. But that has not been the case.
Astronomers claim that the Most massive old stars may also be the dustiest. These thick blankets of dust can obscure starlight to the point of making them completely undetectable. Webb’s new observations support this hypothesis.
“I have argued for this interpretation, but even I did not expect to see an example as extreme as SN 2025pht,” Kilpatrick said. “That would explain why these more massive supergiants are absent, because they tend to be dustier.”
In addition to the presence of dust itself, the dust composition was also surprising. While red supergiants tend to produce oxygen- and silicate-rich dust, this star’s dust appeared carbon-rich. This suggests that powerful convection in the star’s final years may have extracted carbon from its interior, enriching its surface and changing the type of dust it produces.
“The infrared wavelengths from our observations overlap with an important feature of silicate dust that is characteristic of some red supergiant spectra,” Kilpatrick said. “This tells us that the wind was very rich in carbon and less rich in oxygen, which is also surprising for a red supergiant of this mass.”
A new era for stellar explosions
The new study marks the first time astronomers have used the Webb Telescope to directly identify the parent star of a supernova, opening the door to many other discoveries. By capturing light across the near- and mid-infrared spectrum, Webb can reveal hidden stars and provide the missing pieces of the puzzle of the life and death of the most massive stars.
The team is now looking for similar red supergiants that could, in the future, explode as supernovae. Observations made by NASA’s upcoming Nancy Grace Roman Space Telescope could help in this search. Roman will have the resolution, sensitivity and infrared coverage to see these stars and potentially witness their variability as they expel large amounts of dust near the end of their lives.
“With the launch of JWST and the upcoming launch of Roman, this is an exciting time to study massive stars and supernova progenitors,” said Kilpatrick. “The quality of the data and the new discoveries we will make will exceed anything observed in the last 30 years.”
