Irvine, CA — Cosmologists have discovered two supernovae further away than any previously detected, by using a new technique that could help find other dying stars at the edge of the universe.
This method has the potential to allow astronomers to study some of the very first supernovae and could advance the understanding of how galaxies form, how they change over time and how the Earth came to be.
The supernovae Jeff Cooke of UC Irvine and colleagues found occurred 11 billion years ago. The next-furthest large supernova known occurred about six billion years ago.
Typically, cosmologists find supernovae by comparing pictures taken at different times of the same swath of sky and looking for changes. Any new light could indicate a supernova. Cooke built upon this idea by blending pictures taken over the course of a year, then comparing them with image compilations from other years.
"If you stack all of those images into one big pile, then you can reach deeper and see fainter objects," Cooke said. "It's like in photography when you open the shutter for a long time. You'll collect more light with a longer exposure."
Doing this with images from the Canada-France-Hawaii Telescope in Hawaii, Cooke found four objects that appeared to be supernovae. He used a Keck telescope to look more closely at the spectrum of light each object emitted and confirmed that that's really what they were.
"The universe is about 13.7 billion years old, so really we are seeing some of the first stars ever formed," Cooke said.
The findings appear in Nature.