This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Astronomers using the James Webb Space Telescope have identified one of the most distant exploding stars ever confirmed. The supernova, SN 2023aeaf, was found at a redshift of 3.195—so far away that its light has been traveling for roughly 11.7 billion years.
The study, published in The Astrophysical Journal on Aug. 13, offers a close-up look at how massive stars die in the young universe's primitive, metal-poor conditions. Massive stars exploding in a core-collapse supernova explosion can be used as tracers for actively forming stars and the physical consequences their explosive deaths exert on the surrounding gas cloud. These explosions actively reshape the environment and set the stage for the next generation of stars to form.
Their rate of occurrence tells astronomers indirectly about how vigorously stars were forming throughout the universe's history. But almost everything astronomers know about how these explosions actually behave comes from nearby, relatively recent examples. Because the early universe had very low metal content, a major question persists over whether these explosions behaved differently far back in the early universe.
Testing this requires finding and studying distant supernova candidates, which are extremely faint and therefore hard to detect. Thanks to its exceptional sensitivity, the James Webb Space Telescope (JWST) has expanded the sample of these ultra-distant explosions through deep imaging surveys such as JADES and COSMOS-Web. In this study, astronomers report one such supernova, SN 2023aeaf, found in the COSMOS-Web survey.
Spectroscopic analysis has confirmed its redshift of z = 3.195, corresponding to a time when the universe was only about 2 billion years old. In this work, Valeria Aparicio of the Institute for Astronomy at the University of Hawai'i and colleagues analyze this explosion to determine its classification and the properties of its host galaxy. Using careful comparisons of its brightness pattern over time, called the light curve, and color evolution with simulated populations of supernovae, the team classified it as a Type II supernova.
This type of explosion occurs when a massive star exhausts its nuclear fuel and its iron core collapses under its own gravity. The spectrum is marked by hydrogen lines, as the star still has its hydrogen-rich outer envelope intact when it dies. The team found this classification had a probability of 97.2%.
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