The size of a star two billion years after the Big Bang, has been measured by a team of researchers led by the University of Minnesota Twin Cities. Detailed images show the supernova cooling. It can help scientists learn more about the stars and galaxies that existed in the early Universe.
The study was published in the journal Nature. The title is ‘Shock cooling of a red-supergiant supernova at redshift 3 in lensed images.’
What can be gleaned from the supernova images?
“This is the first detailed look at a supernova from a much earlier epoch of the Universe’s evolution,” said Patrick Kelly, the paper’s lead author and an associate professor at the University of Minnesota School of Physics and Astronomy.
“It’s very exciting because we can learn in detail about an individual star when the Universe was less than a fifth of its current age. We can start to understand if the stars that existed many billions of years ago are different from the ones that exist today.”
The observed supernova was 500 times larger than the Sun. It was located at redshift three, 60 times farther away than any other supernova observed in this detail.
Due to a phenomenon known as gravitational lensing, the team identified multiple detailed images of the supernova. They have used the University of Minnesota’s Large Binocular Telescope and data from the Hubble Space Telescope. A mass, such as that found in a galaxy, bends light, magnifying the light emitted by the star.
“The gravitational lens acts as a natural magnifying glass, multiplying Hubble’s power by an order of magnitude,” Kelly explained. “We see three images here. Even though they are visible at the same time, they depict the supernova at different ages separated by several days. We see the supernova rapidly cooling. It allowed us to reconstruct what happened and study how the supernova cooled in its first few days using only one set of images. It allows us to see a supernova rerun.”
Learning more about the origins of the Universe
The findings were combined with another supernova discovery. That discovery made by Kelly in 2014 to estimate how many stars exploded in the early Universe. The researchers discovered that there were probably a lot more supernovae than previously thought.
“The deaths of massive, short-lived stars are marked by core-collapse supernovae.” The number of core-collapse supernovae detected can be used to calculate how many massive stars formed in galaxies when the Universe was much younger, according to Wenlei Chen, first author of the paper and postdoctoral researcher at the University of Minnesota School of Physics and Astronomy.