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Researchers `see' dawn of the universe

Astronomers may have detected the dawn's early light -- light from around the dawn of the universe, that is.

Researchers from NASA's Goddard Space Flight Center in Maryland believe they captured traces of radiation from long-extinguished stars that were "born" during the universe's infancy.

The research represents the first tangible -- but not conclusive -- evidence of these earliest stars, which are thought to have produced the raw materials from which future stars, including our sun, were created.

The Big Bang, the explosion believed to have created the universe, is thought to have occurred 13.7 billion years ago. About 100 million years later, hydrogen atoms began to merge and ignite, creating brightly burning stars. Just what these stars were like wasn't clear.

"Where they lived, how big they were, how much light they emitted, whether they even existed, we weren't sure," said astrophysicist Alexander Kashlinsky, the lead author of the article in yesterday's issue of the journal Nature. "What we've done, we think, is obtain the first information about these stars."

Kashlinsky's team used NASA's Spitzer Space Telescope to measure the cosmic radiation, which is infrared light invisible to the human eye, in a small sliver of the sky. The team then subtracted the radiation levels of all known galaxies and suggested that the leftover measurements include radiation given off by those earliest stars.

The exercise was like taking a recording of a stadium full of loud people and subtracting the noise of every person except one to hear the voice of that single individual.

If the team's conclusions are correct, the study will advance understanding of how the universe originally lit up.

Richard Ellis, an astronomy professor at the California Institute of Technology, cautiously agreed with Kashlinsky's conclusion.

In a commentary published by Nature, Ellis wrote, "Even a minor blunder in removing these foreground signals might lead to a spurious result," but he said in an interview that Kashlinsky's team did the best job it could given the constraints of the technology used.

Ned Wright, an astronomy professor at UCLA, was more doubtful. He argued that the process of removing the radiation contribution of other stars is too imprecise to make the team's conclusions valid.
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