Utilizing data from the NASA/ESA/CSA James Webb Space Telescope, researchers have, for the first time, pinpointed the precursor to a proximate supernova—specifically, a red supergiant star obscured by dense, dust-laden envelopes that rendered it imperceptible to prior observational instruments.
The principal visual depiction on the left presents a composite perspective of the spiral galaxy NGC 1637, integrating imagery from both Webb and Hubble, with the area of focus situated in the upper right quadrant. The subsequent three panels offer an in-depth examination of a red supergiant star, captured both prior to its cataclysmic explosion and in its immediate aftermath. Notably, this star was undetectable in the Hubble imagery preceding the SN 2025pht detonation but became discernible in the Webb observations. The July 2025 snapshot from Hubble illustrates the incandescent remnants of this cosmic event. Credit for the imagery: NASA / ESA / CSA / STScI / C. Kilpatrick, Northwestern / A. Suresh, Northwestern / J. DePasquale, STScI.
The celestial event in question, identified as SN 2025pht, was initially detected within the galaxy NGC 1637 on June 29, 2025.
In response to this discovery, the astronomical community rapidly mobilized their resources to conduct a more thorough investigation of the supernova.
However, Charlie Kilpatrick, an astronomer affiliated with Northwestern University, and his research associates opted to delve into archival data, aiming to utilize pre-explosion imagery to precisely identify which specific star among numerous candidates had undergone the explosive demise.
Webb’s MIRI (Mid-Infrared Instrument) and NIRCam (Near-Infrared Camera) captured images of NGC 1637 in 2024, revealing a solitary red supergiant star positioned precisely where the supernova now emanates its brilliance.
“We had anticipated an event like this—a supernova erupting within a galaxy that Webb had previously documented,” stated Dr. Kilpatrick.
“By amalgamating data sets from both Hubble and Webb, we were able to comprehensively characterize this star for the very first time.”
Aswin Suresh, a postgraduate student at Northwestern University, commented, “This represents the most exceptionally red and dust-enshrouded red supergiant we have observed exploding as a supernova.”
This pronounced presence of dust may offer a solution to a persistent enigma in astrophysics, often referred to as the conundrum of the absent red supergiants.
Astrophysicists generally anticipate that stars of the greatest mass, upon exploding as supernovae, would also exhibit the highest luminosity and brightness.
Consequently, they should be readily identifiable in images captured before their explosive transformation. However, this has not consistently been the case.
One plausible hypothesis suggests that the most massive stars in their late stages of evolution are also the most prolific producers of dust.
Should these stars be encompassed by substantial volumes of particulate matter, their emitted light could be so significantly attenuated as to render them undetectable.
The observational findings from Webb concerning SN 2025pht lend credence to this conjecture.
“I have consistently advocated for this interpretation, yet even I did not foresee the extreme manifestation observed with SN 2025pht,” Dr. Kilpatrick remarked.
“This phenomenon would elucidate the scarcity of observations for these more massive supergiants, as they tend to accumulate more dust.”
Furthermore, the researchers discovered that the circumstellar material surrounding the star is predominantly composed of carbon—an unexpected revelation, given that scientific understanding would typically predict silicate-based dust in such an environment.
They theorize that this carbonaceous component may have been brought to the star’s surface from its internal regions shortly before its explosive end.
“Having access to mid-infrared observational capabilities was instrumental in precisely determining the composition of the dust we were observing,” Suresh explained.
The scholarly article detailing these findings was published in October 2025 in the prestigious journal, the Astrophysical Journal Letters. The accessible link is: paper.
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Charles D. Kilpatrick et al. 2025. 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. ApJL 992, L10; doi: 10.3847/2041-8213/ae04de
