Astronomers discover the oldest known spiral galaxy
The image below is a picture of the oldest known spiral galaxy that scientists say formed 12.4 billion years ago. The ancient galaxy is named BRI 1335-0417, and the image was taken by the Atacama Large Millimeter\submillimeter Array (ALMA) telescope in Chile. The image is notable because it shows that spiral galaxies were formed as soon as 1.4 billion years after the Big Bang. Photographs such as this are essentially looking back in time because we see it as it was over a billion years ago because of the amount of time it took its light to reach us.
Astronomer Dr. Kai Noeske says the photograph shows that galaxies started to resemble modern galaxies roughly 1 billion years earlier than previously believed. Scientists say spiral galaxies are more mature forms of galaxies. In the early stages of a galaxy, dark matter brings hot gases together in clumps that create stars. The stars then merge together to create larger galaxies which early in their lives are misshapen. Eventually, the galaxies begin rotating, creating disk-like shapes.
Spiral galaxies occur when those disks start to be disturbed. Noeske says that other than being pretty to look at, the spiral arms also compress the gas to become catalysts for new star formation. Currently, scientists believe galaxy formation peaked about 3.3 billion years after the Big Bang when most stars present in the universe were formed. It was a surprise that BRI 1335-0417 already had structures similar to nearby galaxies long before the active phase of galaxy formation. Prior to discovering BRI 1335-0417, the oldest known galaxy was formed 2.5 billion years after the Big Bang.
That makes BRI 1335-0417 older by about 1 billion years. The new findings change scientific knowledge about how and when galaxies formed and evolved into what we see today. Astronomers note that while BRI 1335-0417 is the oldest known spiral galaxy, it’s not the oldest galaxy ever observed. That title goes to a galaxy called GNz11 spotted last December that formed 13.4 billion years ago, a mere 400 million years after the Big Bang.
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May 23, 2021 at 11:12AM