A significant astronomical breakthrough occurred when the James Webb Space Telescope identified the oldest supernova ever observed, dating back to a time when the universe was just 730 million years old. This discovery emerged from the remnants of a powerful gamma-ray burst, which had traveled through space from a distant source. The event pushes back the record for stellar explosions previously held by a supernova that occurred 1.8 billion years after the Big Bang.
The gamma-ray burst was first detected on March 14, 2023, by the SVOM mission (Space-based multi-band astronomical Variable Objects Monitor). Within hours, three additional telescopes collaborated to locate the origin of the burst and establish its timing within the cosmic timeline. According to Andrew Levan, an astrophysics professor at Radboud University and lead author of a paper published in Astronomy and Astrophysics Letters, “There are only a handful of gamma-ray bursts in the last 50 years that have been detected in the first billion years of the Universe. This particular event is very rare and very exciting.”
Decoding the Cosmic Mystery
Gamma-ray bursts generally last just seconds, often resulting from the collision of two neutron stars or between a neutron star and a black hole. However, this burst lasted an unusual 10 seconds, indicating it likely resulted from the explosive death of a massive star. The James Webb Space Telescope made its observations on July 1, 2023, approximately three months after the initial detection of the gamma-ray burst. This interval allowed the supernova’s brightness to increase, enhancing its visibility.
Astronomers noted that supernovae typically brighten rapidly over weeks. Yet, given this supernova’s early occurrence in the universe, its light had stretched due to the expansion of space over time. As light stretches, the unfolding of events appears to take longer. Once researchers focused on the ancient supernova, they compared its characteristics to more recent explosions closer to Earth. Contrary to their expectations, they found striking similarities.
“We went in with open minds,” stated Nial Tanvir, a professor at the University of Leicester and co-author of the paper. “And lo and behold, Webb showed that this supernova looks exactly like modern supernovae.” The findings suggest that despite the differences in the composition and lifespan of stars in the early universe—primarily containing fewer heavy elements—this supernova’s behavior aligns closely with those observed today.
Future Observations and Implications
Looking ahead, the team of astronomers plans to utilize the James Webb Space Telescope to observe the afterglow of distant gamma-ray bursts. This research aims to deepen their understanding of galaxy evolution over time. “That glow will help Webb see more and give us a ‘fingerprint’ of the galaxy,” Levan explained, highlighting the telescope’s potential to reveal insights into the universe’s history.
The implications of this discovery extend beyond mere academic interest; they enhance our understanding of the universe’s evolution and the life cycles of stars. As the James Webb Space Telescope continues its groundbreaking work, the astronomical community eagerly anticipates further revelations about the cosmos’s earliest moments.
