Astronomers have solved a decades-old cosmic mystery using the James Webb Space Telescope, capturing the first-ever mid-infrared image of a doomed star just before it exploded. A team led by Northwestern University researchers identified a massive red supergiant, previously hidden from view, as the source of a supernova detected in 2025. The discovery suggests that these stellar behemoths have not been inexplicably vanishing before their explosive deaths, but have instead been concealed within thick shrouds of dust that only the Webb’s powerful infrared instruments could penetrate.
The finding provides the most detailed glimpse yet of the final moments of a red supergiant and addresses a significant gap between theoretical models and astronomical observations. For years, scientists wondered why so few red supergiants—predicted to be the most common sources of a specific type of supernova—were actually seen exploding. By analyzing archival Hubble Space Telescope images alongside new Webb data, the team located the progenitor star of supernova SN2025pht. They found it to be one of the dustiest and reddest such stars ever observed, a behemoth shining with the light of 100,000 suns yet dimmed more than a hundredfold by its own dusty veil.
A Long-Standing Astronomical Puzzle
The universe is filled with massive stars, and red supergiants represent one of the final stages in their life cycles. These stars, among the largest in the cosmos, are expected to end their lives in spectacular explosions known as Type II supernovae. Theoretical models of stellar evolution have long predicted that red supergiants should be the most frequent progenitors for these cosmic blasts. One of the most famous examples of a red supergiant is Betelgeuse, the bright reddish star in the constellation Orion.
Despite these predictions, astronomers faced a persistent observational problem: they simply weren’t finding the expected number of red supergiants linked to supernovae. This discrepancy, often called the “red supergiant problem,” created a frustrating inconsistency between theory and reality. It led to speculation about whether the models were flawed or if these stars were somehow transforming into a different, less visible state immediately before their demise. The answer, it turns out, was not that the stars were missing, but that they were exceptionally good at hiding.
Webb’s Infrared Investigation
The breakthrough came with the unique capabilities of the James Webb Space Telescope. While optical telescopes like the Hubble Space Telescope are powerful, their vision can be blocked by cosmic dust, which absorbs and scatters shorter, bluer wavelengths of light. Infrared light, however, can pass through these dusty clouds, allowing Webb to see what was previously invisible. Using Webb’s sensitive mid-infrared instruments, a research team led by Charlie Kilpatrick of Northwestern University examined the location of supernova SN2025pht, which was first detected on June 29, 2025. The explosion occurred in the spiral galaxy NGC 1637, located approximately 40 million light-years from Earth.
By cross-referencing Webb’s new observations with archival data from Hubble, the team was able to pinpoint the exact star that had exploded. In the older Hubble images, nothing was visible at the location in optical light. But in the Webb data, a bright source emerged from the darkness—the progenitor star, finally revealed. “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,” Kilpatrick stated. This marked the first time a supernova progenitor had been successfully identified using mid-infrared wavelengths.
An Unusually Red and Dusty Star
The star that spawned SN2025pht was no ordinary red supergiant. The data revealed it was exceptionally bright, with a luminosity about 100,000 times that of our sun. However, it was enveloped in such a thick cocoon of dust that it appeared more than 100 times dimmer in visible light than it would have otherwise. This dense shroud of dust preferentially blocked bluer light, causing the star to appear intensely red.
Aswin Suresh, a graduate student at Northwestern and a key co-author of the study published in The Astrophysical Journal Letters, described the finding’s significance. “It’s the reddest, dustiest red supergiant that we’ve seen explode as a supernova,” he said. This extreme level of dustiness explains why it was completely invisible to Hubble and why so many other similar stars may have been missed in past supernova surveys. The dust is likely carbon-rich, produced by the star itself as it shed its outer layers in the final phase of its life before the core collapse that triggered the explosion.
Closing the Gap Between Theory and Observation
The successful identification of this dust-obscured progenitor provides the strongest evidence yet that the red supergiant problem was an observational bias rather than a flaw in stellar theory. It suggests that a significant population of red supergiants undergo a period of intense mass loss and dust production right before they go supernova, effectively cloaking themselves from view in visible light. With Webb’s infrared vision, astronomers can now systematically search for these hidden progenitors in the sites of recent supernovae, building a more complete census of how massive stars die.
This discovery reshapes astronomers’ understanding of the final evolutionary stages of massive stars. It implies that previous supernova observations may have misjudged the true luminosity and characteristics of their progenitor stars because the obscuring dust was not accounted for. As Kilpatrick noted, the intense redness of SN2025pht suggests “that previous explosions might have been much more luminous than we thought because we didn’t have the same quality of infrared data that JWST can now provide.” The ability to detect and analyze these dusty environments opens a new window into the complex processes that occur just moments, in cosmic terms, before a star’s cataclysmic death, leaving behind a neutron star or a black hole.
