Astronomers Discover Hidden Supergiant Star Using JWST

A team of scientists at Northwestern University has unveiled a significant discovery regarding massive red supergiant stars, which are theorized to be the primary progenitors of supernovae. Utilizing the advanced capabilities of the James Webb Space Telescope (JWST), researchers identified a supernova, designated SN2025pht, that offers new insights into these elusive celestial giants. The findings suggest that many supernovae may be obscured by dust, hindering their visibility.

SN2025pht was first detected on June 29, 2025, in the galaxy NGC 1637, located approximately 40 million light-years from Earth. The observations revealed that this supernova’s progenitor star was exceptionally bright, shining around 100,000 times brighter than our Sun. However, the intense surrounding dust dimmed its light significantly, making it appear over 100 times fainter in visible light than it actually was. The researchers discovered that the dust not only obscured the star but also altered its color, giving it a surprisingly red appearance due to the blocking of shorter, bluer wavelengths.

Lead scientist Charlie Kilpatrick expressed the excitement surrounding this study, stating, “For multiple decades, we have been trying to determine exactly what the explosions of red supergiant stars look like… With JWST, 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.” This study marks a pivotal moment as it combines data from both JWST and the Hubble Space Telescope to characterize the star in unprecedented detail.

Unraveling the Mystery of Red Supergiants

Red supergiants are among the largest stars in the universe, and when their cores collapse, they explode as Type II supernovae, often resulting in a neutron star or black hole. Despite their theoretical prominence in the stellar lifecycle, astronomers have struggled to locate these massive stars before they explode. The prevailing hypothesis suggests that the most massive stars may also be the dustiest, rendering them nearly invisible. The recent observations from the JWST support this theory, providing potential explanations for the challenges faced by astronomers in identifying red supergiant progenitors.

Notably, the composition of the surrounding dust was unexpected. Traditionally, red supergiants produce oxygen-rich, silicate dust; however, the dust surrounding SN2025pht appeared rich in carbon. This finding implies that powerful convection processes within the star could have brought carbon from its interior to the surface, thus altering the type of dust produced during its final stages.

A New Era in Stellar Observation

The implications of this research extend beyond just one supernova. This study represents the first successful identification of a supernova progenitor star using the JWST, heralding a new era for astronomical observations. The capabilities of the JWST, which captures light across the near- and mid-infrared spectrum, allow astronomers to uncover hidden stars that have previously eluded detection.

The team is now focused on locating additional red supergiants that might soon explode as supernovae. Future observations by NASA’s upcoming Nancy Grace Roman Space Telescope are anticipated to enhance this search. With its advanced resolution and sensitivity, the Roman telescope will be able to observe these stars and their changing behavior as they shed large amounts of dust in their final stages.

The findings of this study have been published in The Astrophysical Journal Letters, under the title “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.” This research not only sheds light on the life cycles of massive stars but also opens up new avenues for understanding the processes that govern their evolution and eventual demise.