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Apr 28, 2009
An international team of astronomers last week detected the most distant gamma-ray burst ever recorded, light that was emitted when the universe was less than 5 percent of its present age.
The burst, called GRB 090423 (after the date it was first seen), appears to signal the death throes of a massive star in the very early universe, just 630 million years after the big bang, according to NASA. (Current estimates peg the universe's age at around 13.7 billion years.)
NASA's Swift satellite picked up the short-lived burst Thursday—gamma-ray bursts usually last just minutes, even seconds—and a suite of follow-up observations of the explosion's afterglow at telescopes around the globe enabled an age estimate.
Jan 7, 2009 | 3
LONG BEACH, CALIF.—You might think that the universe 11.5 billion years ago was in a more primitive state than it is today. Barely two billion years had passed since the big bang, our Milky Way galaxy was still taking shape, and billions more years would pass before the sun pulled itself together. Yet astronomers have come to realize that the universe was actually quite precocious. Even by that early stage, much of it had already seen many cycles of stellar birth and death.
The latest hint of its precocity came yesterday when astronomers announced that cosmic gas in that period, seen when backlit by a gamma-ray burst (a gigantic stellar explosion), contained molecular hydrogen and carbon monoxide—the first time astronomers have discovered molecules, as opposed to isolated atoms or ions, in the light of a gamma-ray burst. The molecules’ presence indicates that the galaxy where the burst occurred was nearly as chemically developed as the present-day Milky Way. Jason Xavier Prochaska of the University of California, Santa Cruz, and his colleagues announced the discovery at the American Astronomical Society’s meeting being held here this week.
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