Light from a star that exploded over 13 billion years ago is just now reaching Earth. The star is about 13.1 billion light years away and sets the record for the farthest object in space to be observed, according to two separate studies in Nature magazine.
The previous record-holder was a galaxy 150 million years younger than the exploded star.
The explosion is known as a gamma-ray burst. It consists of short lived bursts of light particles, or photons, that are emitted during the deaths of massive stars.
“In astronomy, a larger distance … corresponds to an earlier time in cosmic history, because it takes longer for a farther-away photon, which travels at finite speed, to reach Earth,” says Bing Zhang from the University of Nevada in the magazine.
This gamma-ray burst, named GRB 090423, shows stars were already forming 630 million years after the Big Bang. The burst occurred when the universe was about nine times smaller than it is today, Zhang says.
About 400,000 years after the Big Bang, atoms are thought to have formed, Zhang says. By 800 to 900 million years after the Big Bang, photons knocked electrons out of neutral atoms and ended the cosmic “Dark Age.”
GRB 090423 falls during the little-understood “Dark Age” and will provide clues to the nature of early stars, according to the studies, led by Nial Tanvir and Ruben Salvaterra.
By Lindsey Anderson
Photo: The gamma-ray burst is the small, very red source in the center of this image. The red color is indicative of its great distance – about 13.1 billion light years – since all the optical light has been absorbed by intergalactic hydrogen gas, leaving only infrared light. All the other galaxies and stars in the image are much closer to us and just happen lie in the same part of the sky. (A.J.Levan & N.R.Tanvir)
Posted at 04:05 PM/ET, October 31, 2009 in Space, NASA and astronomy