Earlier this year, something incredible happened in space. A powerful gamma-ray burst—an explosion of cosmic light—reached us from way back in the universe’s early days. This burst, which was traced to a moment just millions of years after the Big Bang, had left many puzzled about its origins. But the Webb telescope came to the rescue, revealing the first signs of a star’s tragic end.
This supernova, observed by Webb when the universe was just 730 million years old, is now the oldest stellar explosion we’ve ever recorded. It set a new benchmark, surpassing the previous record of an explosion spotted 1.8 billion years after the Big Bang.
Andrew Levan, an astrophysics professor at Radboud University, noted how crucial Webb’s findings are. “Only Webb could directly show that this light is from a supernova,” he explained. This discovery tells us that we can see individual stars from a time when the universe was only 5% as old as it is today.
On March 14, the SVOM mission (Space-based multi-band astronomical Variable Objects Monitor) was the first to detect the gamma-ray burst. Shortly after, three other telescopes gathered around to pinpoint where in the sky the burst originated and when it occurred.
Levan emphasized the rarity of such events. “There have only been a handful of gamma-ray bursts detected in the first billion years of the Universe,” he said. “This event is both rare and exciting.” Typically lasting only a few seconds, gamma-ray bursts are usually caused by the collision of neutron stars or between a neutron star and a black hole. However, this one lasted about 10 seconds, suggesting it was an explosive end for a massive star.
The Webb telescope began its observations about three months after the gamma-ray burst was recorded. This time allowed the supernova to brighten, making it easier to spot. Supernovae usually brighten quickly, but because this one happened so early in the universe, its light was stretched over time, making the viewing experience quite different.
Once astronomers focused on the ancient supernova, they found it surprisingly similar to more recent ones. Despite stars back then having fewer heavy elements and being much more massive, they still looked like today’s supernovae. Nial Tanvir, a professor at the University of Leicester, commented, “We went in with open minds, and lo and behold, Webb showed that this supernova looks exactly like modern supernovae.”
What’s next for these astronomers? They plan to use Webb to study the afterglow of future gamma-ray bursts. This light could reveal more about galaxies and their evolution over time. As Levan put it, “That glow will help Webb give us a ‘fingerprint’ of the galaxy.”
This remarkable discovery sheds new light on our understanding of cosmic events and the nature of the early universe, showcasing the power of modern technology in unraveling the mysteries of our existence. For further reading about gamma-ray bursts and their significance, check out this insightful article from NASA.
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