James Webb Detects Earliest Supernova Ever Observed
The James Webb Space Telescope (JWST) has confirmed the source of the powerful gamma-ray burst GRB 250314A. It was identified as the explosion of a massive star (supernova) that occurred when the Universe was just 730 million years old.
This discovery sets a new record: the previous most distant confirmed supernova dated back to an epoch when the Universe was 1.8 billion years old. Additionally, this marks the first time the telescope has successfully imaged the host galaxy of such an ancient event.
Key Details of the Discovery:
- Timeline: The initial signal was detected in mid-March 2025 by the Franco-Chinese SVOM telescope, after which the coordinates were refined by the Swift and VLT observatories, along with other ground-based telescopes.
- The Expansion of the Universe: Due to the immense distance and cosmological redshift, the observed duration of the explosion was stretched out. While supernovae typically brighten over the course of weeks, in this case, the process took months. JWST conducted observations 3.5 months after the burst, coinciding with the calculated peak brightness.
- A Scientific Puzzle: Spectral analysis revealed that this ancient supernova is surprisingly similar to modern explosions of massive stars. This came as a surprise to astrophysicists, as it was hypothesized that stars in the early Universe (the Epoch of Reionization) would differ significantly from modern stars in terms of chemical composition (metallicity) and life cycle.
"Only Webb can definitively show that this light comes from a collapsing massive star, allowing us to study individual objects that existed when the Universe was only 5% of its current age," noted Professor Andrew Levan, the study’s lead author.
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