Astronomers saw a distant supernova less than 6 hours after it blew up

The Hubble Space Telescope has captured a distant star exploding earlier than ever before, allowing scientists to observe the first eight days of a star's violent death.

Abell 370 is located 5 billion light years away from Earth. Frontier Fields of NASA, ESA/Hubble, and HST

A massive star's core ran out of fuel and collapsed in on itself before exploding outwards in a powerful supernova about 21 billion light years away. 

The Hubble Space Telescope detected the explosion less than 6 hours later, which is the earliest we have ever seen such a distant supernova, and those images have allowed astronomers to determine the properties of the original star.

Wenlei Chen of the University of Minnesota and his colleagues discovered this supernova while looking through archival Hubble data from 2010. It was visible due to gravitational lensing, a phenomenon in which the gravity of a massive object - in this case, a galaxy in a nearby cluster called Abell 370 - acts as a magnifying glass for the light behind it.

The light from the supernova is magnified and duplicated in the Hubble image. When light from the background object is dragged in multiple directions around the foreground object, multiple images of the background object are created. Because the light must travel a different distance on each unique path, these images provide snapshots of the supernova's evolution at various stages.

This supernova's three images show a faint, blue spot of light growing brighter and redder. This indicates that we are witnessing the expansion and cooling of stellar material immediately following the initial explosion. The first image was created about 5.8 hours after the supernova began, the second about two days later, and the third about six days later.

During that time, the supernova cooled from nearly 100,000°C to less than 10,000°C, according to the researchers. The light's details also allowed the researchers to calculate that the exploding star had a radius about 530 times that of the sun, classifying it as a red supergiant.

"Core-collapse supernovae mark the death of massive stars, which are short-lived because they burn up faster than stars of less mass," Chen explains. "As a result, the rate of core-collapse supernovae should track the rate of massive star formation." This means that studying supernovae like this one may help us understand how stars formed in the early universe. The James Webb Space Telescope, with its ability to peer deep into the early universe, will be a powerful tool in this search, according to Chen.

Journal citation: Nature, DOI: 10.1038/s41586-022-05252-5


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