Most Distant Object Found; Light Pierced "Dark Age" Fog

October 28, 2009

The most distant object yet spied in the universe is the remnant of a star about 13 billion light-years from Earth that sheds new light on the earliest days of the universe.

Two different teams of astronomers studied a brief but powerful flash of light, called a gamma-ray burst, from the star explosion.

Because of the time it takes for light to travel such distances, scientists think the exploded star must have been born about 600 million years after the big bang, when the universe was just 4 percent of its current age.

This means that the gamma-ray burst offers an unprecedented peek into a mysterious period known as the cosmic dark ages, which lasted from shortly after the big bang until about 900 to 800 million years thereafter.

Astronomers think the first stars started forming during the dark ages. But few such stars have ever been spotted, because the early universe was fogged with hydrogen gas that shrouded the starlight.

"Our group, and many others worldwide, have been working for years to catch such a rare event," said Ruben Salvaterra of Italy's Brera Astronomical Observatory, who was lead author on one of the studies.

The discovery gives researchers hope of spotting still older objects, including the first generation of stars that ever formed.

"Gamma-ray bursts are the most luminous phenomena in the universe," said Dale Frail, whose team tracked radio emissions from the dying star using the National Radio Astronomy Observatory in Socorro, New Mexico. (See pictures of a gamma-ray burst that was visible from Earth to the naked eye.)

"This means that a bright gamma-ray burst could be detected out to the earliest times in the age of the universe."

Text Message From Space

The newfound gamma-ray burst, dubbed GRB 090423, was first picked up in April by sensors aboard a NASA satellite called Swift.

The probe instantly swiveled its mirrors to monitor the burst, and soon after astronomers worldwide received alerts.

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