NASA’s Webb telescope detects the earliest known supernova from 730 million years after the Big Bang

NASA’s James Webb Space Telescope has identified the earliest known supernova, which exploded when the universe was approximately 730 million years old.

The supernova, designated GRB 250314A, was first detected as a gamma-ray burst in mid-March by the SVOM mission, a Franco-Chinese telescope designed to monitor transient astronomical events.

Following the initial detection, NASA’s Neil Gehrels Swift Observatory, the Nordic Optical Telescope and the European Southern Observatory’s Very Large Telescope confirmed the distance and infrared afterglow of the event.

Webb’s near-infrared observations, conducted on July 1, allowed astronomers to locate the faint host galaxy of the supernova, providing the earliest direct detection of such an event in the universe’s history.

Identification of the Supernova and Gamma-Ray burst

Gamma-ray bursts are very strong, yet very short, flashes of radiation, and they are at times associated with the death of massive stars in an explosive manner.

In this instance, the gamma-ray burst was detected for a period of 10 seconds, which is a typical duration of long bursts associated with supernovae.

Swift's X-ray source localization took 90 minutes from the moment of the alert, while the Nordic Optical Telescope recorded an infrared afterglow 11 hours later.

The Very Large Telescope evaluated that the object formed 730 million years after the Big Bang.

Observations by Webb were conducted three and a half months after the gamma-ray burst, as the supernova was expected to attain its maximum brightness during that period.

NASA has stated that Webb's high-resolution near-infrared images were able to resolve both the supernova and its faint host galaxy, thereby providing the earliest direct observation of a massive star undergoing a supernova collapse.

Comparison with nearby Supernovae

Researchers compared supernova GRB 250314A with modern, nearby supernovae to evaluate similarities.

The earliest supernova appears consistent with known supernova patterns despite occurring during the universe’s first billion years.

While early stars were likely more massive and contained fewer heavy elements, the observed supernova exhibited light and temporal characteristics comparable to those of contemporary supernovae.

Co-authors Andrew Levan of Radboud University and the University of Warwick, Benjamin Schneider of the Laboratoire d'Astrophysique de Marseille and Nial Tanvir of the University of Leicester contributed to these observations and analysis, which were reported in Astronomy and Astrophysics Letters.

The Webb data provide a direct view of stellar explosions during the early stages of the universe without relying on secondary modeling or simulations.

Observation of the host Galaxy

Webb also captured the faint host galaxy of the supernova, a distant galaxy that appears as a reddened cluster of pixels in the near-infrared images.

Emeric Le Floc’h of CEA Paris-Saclay reported that the galaxy exhibits characteristics similar to other galaxies from the same era.

Observing the host galaxy allows researchers to study the environments where early supernovae occurred.

Future Webb observations will focus on capturing the afterglow of gamma-ray bursts in distant galaxies, providing further information on the properties of early galaxies and their stellar populations.

The observations were conducted under a Director’s Discretionary Time program approved for rapid response to transient events.

The James Webb Space Telescope, an international program led by NASA with partners from ESA and CSA, continues to provide data on both the local and distant universe.

By identifying supernova GRB 250314A and its host galaxy, Webb has set a new record for the earliest observed supernova, supporting ongoing efforts to study the first stars and galaxies in the universe.

Stay tuned for more updates.