"We got text messages on our mobile phones, and we knew we had to jump into action," said Nial Tanvir, an astronomer at the U.K.'s University of Leicester and lead author of the other optical study.
Different teams of astronomers using telescopes in Hawaii, New Mexico, Chile, and Spain all tracked the massive explosion as it faded away.
Salvaterra and Tanvir's teams published their findings in two separate papers appearing this week in the journal Nature. Frail and colleagues posted their report last week to the Cornell University Web site Arxiv.org.
Breaking Up the Mist
Because of its extreme distance, the newfound gamma-ray burst shows that the star exploded before the dark ages ended thanks to reionization.
During the dark ages, the hydrogen atoms that permeated the universe were uncharged, so the gas blocked much of the radiation that we perceive as starlight.
But over time, light from the first stars ionized the hydrogen, turning it into a charged gas.
When this happened, "the universe went fairly rapidly from being opaque to suddenly being transparent," Tanvir said. "It's like on a foggy day, when the sun comes out and breaks up the mist."
Gamma-ray bursts can shine through the haze of the dark ages, however, since a gamma ray is the most intense type of light known.
By studying more gamma-ray bursts, researchers might be able to figure out when the very first stars appeared and when they began to clear up the fog.
Bing Zhang, of the University of Nevada in Las Vegas, wrote a commentary also appearing in Nature but was not involved in any of the studies.
"The discovery," Zhang wrote, "opens up the exciting possibility of studying the reionization epoch and the preceding cosmic dark ages."
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