An international research
team led by the University of Minnesota Twin Cities has measured the size of a
star dating back 2 billion years after the Big Bang, or more than 11 billion
years ago. Detailed images show the exploding star cooling and could help scientists
learn more about the stars and galaxies present in the early Universe.
The paper is published in Nature, the world’s leading peer-reviewed, multidisciplinary
science journal.
“This
is the first detailed look at a supernova at a much earlier epoch of the
Universe’s evolution,” said Patrick Kelly, a lead author of the paper and an
associate professor in 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, and
begin to understand if the stars that existed many billions of years ago are
different from the ones nearby.”
The
red supergiant in question was about 500 times larger than the sun, and it’s
located at redshift three, which is about 60 times farther away than any other
supernova observed in this detail.
Using
data from the Hubble Space Telescope with follow-up spectroscopy using the
University of Minnesota’s access to the Large Binocular Telescope, the researchers
were able to identify multiple detailed images of the red supergiant because of
a phenomenon called gravitational lensing, where mass, such as that in a
galaxy, bends light. This magnifies the light emitted from the star.
“The
gravitational lens acts as a natural magnifying glass and multiplies Hubble’s
power by a factor of eight,” Kelly said. “Here, we see three images. Even
though they can be seen at the same time, they show the supernova as it was at
different ages separated by several days. We see the supernova rapidly cooling,
which allows us to basically reconstruct what happened and study how the
supernova cooled in its first few days with just one set of images. It enables
us to see a rerun of a supernova.”
Panels A-D
(clockwise from upper left) show several different stages of the supernova: the
location of the host galaxy after the supernova faded, the three images of the
host galaxy and the supernova at different phases in its evolution, the three
different faces of the evolving supernova, and the different colors of the
cooling supernova. Photo credit: Wenlei Chen, NASA
The researchers combined this discovery
with another one of Kelly’s supernova discoveries from 2014 to estimate how
many stars were exploding when the Universe was a small fraction of its current
age. They found that there were likely many more supernovae than previously
thought.
“Core-collapse supernovae mark the deaths of massive, short-lived stars. The number of core-collapse supernovae we detect can be used to understand how many massive stars were formed in galaxies when the Universe was much younger,” said Wenlei Chen, first author of the paper and a postdoctoral researcher in the University of Minnesota School of Physics and Astronomy.
Source: https://cse.umn.edu/college/news/red-supergiant-supernova-images-reveal-secrets-earlier-universe
Journal article: https://www.nature.com/articles/s41586-022-05252-5
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