Astronomers Spot Earliest Known Supernova In Universe Using James Webb Telescope
JWST detects supernova from 730M years after Big Bang, offering rare glimpse of stars in early universe. The event offers scientists a rare glimpse into the final moments of massive stars.
An international team of astronomers has made a groundbreaking discovery, detecting a supernova—the explosive death of a massive star, at an unprecedented distance in the early universe using the James Webb Space Telescope (JWST). The explosion, designated SN in GRB 250314A, occurred when the universe was just about 730 million years old, placing it deep in the era of reionization.
The event offers scientists a rare glimpse into the final moments of massive stars at a time when the first galaxies and stars were forming. The discovery was reported in the academic paper JWST reveals a supernova following a gamma-ray burst at z ≃ 7.3 published in Astronomy & Astrophysics (704, December 2025).
First Flagged By Burst
The supernova was first flagged by a bright burst of high-energy radiation, known as a long-duration Gamma-Ray Burst (GRB), detected on March 14, 2025, by the space-based SVOM monitor. Follow-up observations with the European Southern Observatory’s Very Large Telescope (ESO/VLT) confirmed its extreme distance.
The JWST’s Near-Infrared Camera (NIRCAM) provided the key observations about 110 days after the burst, allowing scientists to separate the explosion’s light from its faint host galaxy.
Supernova Is A Smoking Gun
Dr. Antonio Martin-Carrillo, astrophysicist at UCD School of Physics and co-author of the study, said: “This supernova is the smoking gun linking gamma-ray bursts to the deaths of massive stars. Most supernovae we observe are nearby, but this one gives us a unique window into the stars of the early universe.”
Using models of local GRB-associated supernovae, the team predicted what the emission should look like and found it matched the observed distant supernova remarkably well. The explosion’s brightness and spectral properties closely resemble SN 1998bw, a GRB-associated supernova observed in the local universe.
Massive Stars Are Not Different From Newer Ones
It is suggesting that massive stars from the early universe may not differ significantly from their modern counterparts, despite lower metallicity conditions. The observations also ruled out a much brighter superluminous supernova (SLSN), challenging previous assumptions that stars formed under early-universe conditions would produce markedly different explosions.
Researchers plan a second epoch of JWST observations within the next one to two years, by which time the supernova’s light is expected to fade significantly. This will allow them to fully characterize the faint host galaxy and confirm the supernova’s contribution.
This discovery provides a critical anchor point for understanding stellar evolution in the universe’s infancy and raises new questions about the uniformity of early cosmic explosions.
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