Images showing a red supergiant star exploding – becoming a supernova – more than 11 billion years ago could help scientists learn more about the early universe.
Researchers from the University of Minnesota Twin Cities in the US measured the star’s size from images made up of light that traveled to Earth just two billion years after the Big Bang.
The results of the analysis, showing rapid cooling of the supernova, are published in Nature.
“This is the first detailed look at a supernova at a much earlier time in the evolution of the Universe,” says lead author Patrick Kelly. “It’s very exciting because we can learn more about an individual star when the Universe was less than a fifth of its current age and begin to understand if stars that existed billions of years ago are different. of those nearby.
Science’s best estimates suggest that the Big Bang, at the beginning of the universe, happened around 13.7 billion years ago.
It is likely that the first stars formed only 100 million years after the birth of the universe. But the size, color and life cycle of these early stars and the first galaxies they began to form remain mysterious.
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Astronomers hope that studying early supernovae and other cosmological events in the early universe will provide a better understanding of how stars and galaxies form. Ultimately, it will help us better understand our own place in the universe.
The red supergiant analyzed in the Nature paper was seen at a redshift of z =3, corresponding to an age of about 11.5 billion years. This means that the light from the supernova has traveled 11.5 billion years to reach us. That’s about 60 times farther than any other supernova studied at this level of detail.
The star was 500 times larger than our Sun and has yet to be named. It was noticed in images taken of the Abell 370 galaxy cluster in December 2010 by the Hubble Space Telescope.
Using the University of Minnesota’s access to the Large Binocular Telescope, researchers were able to use tracking spectroscopy to generate detailed images of the red supergiant. The images were made possible by gravitational lensing, where the mass of a galaxy between us and the red supergiant deflects light from the star, magnifying the light it emits.
“The gravitational lens acts like a natural magnifying glass and multiplies Hubble’s power by a factor of eight,” Kelly explains. “Here, we see three images. Although they can be seen at the same time, they show the supernova as it was at different ages several days apart. We see the supernova cooling rapidly, allowing us to essentially reconstruct what happened and study how the supernova cooled in its early days with a single set of images. This allows us to see a replay of a supernova.
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This analysis, in conjunction with work done by Kelly on supernovae since 2014, suggests that there were more stars exploding in the young universe than previously thought.
“Core-collapse supernovae mark the death of massive, short-lived stars,” adds first author Dr. Wenlei Chen, also from the University of Minnesota’s School of Physics and Astronomy. “The number of core-collapse supernovae we detect can be used to understand how many massive stars formed in galaxies when the universe was much younger.”
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