James Webb spots most distant supernova ever recorded

Using the James Webb Space Telescope, astronomers have identified 80 new early supernovae in a patch of sky about as wide as a grain of rice held at arm’s length. Among them is the oldest and most distant supernova ever observed. Imagine a stellar explosion shaking the universe when it was only 1.8 billion years old, on a cosmic time scale of 13.8 billion years.

A Cosmic Detective

James Webb is good more than just a telescope. He is a cosmic detective armed with a Unmatched infrared sensitivitycapable of probing the depths of space for signs of stellar life and death. With its keen gaze, this observatory can detect supernovae almost anywhere it looks in the cosmos, allowing us to go back in time and explore the earliest chapters of our Universe. Some of the exciting discoveries of the James Webb Space Telescope (JWST) are Type Ia supernovae. These objects are the result of a cataclysmic explosion that occurs when a white dwarf, a type of dead star, acquires material from a nearby companion star. When the white dwarf absorbs enough material, it reaches a critical mass, which triggers a runaway thermonuclear reaction on its surface. This reaction then expels the excess material into space in a spectacular explosion that releases an incredible amount of energy. What makes Type Ia supernovae so remarkable is their uniformity in intrinsic brightness. No matter how far away they are, these stellar explosions almost always reach the same maximum brightness. Astronomers then use these objects to measure distances in the Universe with remarkable precision.

An illustration shows a white dwarf beginning to erupt in a Type Ia supernova as it feeds on a companion star. Credit: Robert Lea

Go back in time

The Hubble Space Telescope had previously allowed astronomers to observe supernovae so distant that they existed when the Universe was in its “young adult” phase. With this telescope, however, astronomers can observe supernovae when the cosmos was still “adolescent”, or even in “pre-adolescence”. Some of them erupted when the Universe was less than two billion years old. It was very different then than the one we know today, with much more extreme environments. Furthermore, the cosmos was mostly made of hydrogen and helium. As a result, astronomers expect to see ancient supernovae triggered by the deaths of stars that contained far fewer heavy chemical elements (or “metals”) than the current generation of “metal-rich” stars like the Sun. So comparing these ancient supernovae with massive stars exploding in the local Universe could help astronomers better understand how stars become enriched during their formation with metals forged by the first stars and spread out into the cosmos when they die. In the future, scientists hope to be able to observe the “infancy” of the Universe or even its cosmic beginnings by ideally stumbling upon the death of the first generation of massive starsThe team’s results were presented at a press conference during the 244th meeting of theAmerican Astronomical Society in Madison, Wisconsin, Monday, June 10.