Massive explosions found near the edge of the universe mark the most distant supernovae ever seen. Cosmologists at the University of California, Irvine, used a new method to detect anomalies in faraway galaxies. Using the new method, two supernovae "came to light," revealing that they exploded in their home galaxies approximately 11 billion years ago.
"The universe is about 13.7 billion years old," says Jeff Cooke, the McCue Postdoctoral Fellow in Physics and Astronomy, "so really we are seeing some of the first stars ever formed."
Before the discovery of these two new supernovae, the farthest known supernovae had occurred about 6 billion years ago. The farther and older supernovae will help astronomers learn about how galaxies form and change and how Earth came to be.
"When stars explode," says Cooke, "they spew matter into space. Eventually, gravity collapses the matter into a new star, which could have planets such as Earth around it."
A supernova is the explosion and collapse of a massive star at the end of its life cycle. As the stars are nearing the end of their lives, they eject matter into space. When the exploding shockwave hits this debris, it glows brightly, often outshining the rest of its parent galaxy.
New Method for Detecting Supernovae
The prior most common method to detect supernovae was by comparing pictures of the same patch of sky taken at different times. Any new light source could indicate a supernovae. Cooke's new method just expands upon the old method by comparing pictures taken over the course of many years.
"If you stack all of those images into one big pile, then you can reach deeper and see fainter objects," he says. "It's like in photography when you open the shutter for a long time. You'll collect more light with a longer exposure."
Cooke examined images taken by the Canada-France-Hawaii Telescope and then zeroed in on suspicious objects and used the Keck Telescope to look more closely at the objects' spectrums. Their spectrum results was what confirmed the objects were supernovae.
Supernovae Are Key to Everything Found in Universe
Studying extremely distant supernovae aids astronomers' understanding of what was happening after the Big Bang and how stellar properties have changed since then. Stars form heavier and heavier elements in their core as they progress through their life cycle, so studying supernovae helps shed more light on understanding how the elements essential to forming planets and creating life were initially created and distributed in the universe.
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