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'Baby Boom' for Stars Came Early, New Theory Suggests


Pushing the limits of what is possible with today's most powerful space and ground telescopes, astronomers have come up with a controversial new analysis of what may have happened during the early universe--an epoch too old and distant to probe directly even with today's most powerful technology.

Astronomers have long thought of the very early universe as a dark and quiet place, with only a trickle of new stars beginning to pierce through the gloom. Many felt that a "baby boom" of star birth did not occur until the 15 billion-year-old universe was middle-age.

The new theory, by contrast, suggests that when the universe was just a few hundred million years old, it may have experienced a bright, violent tempest of new stars being born--a torrent of light reminiscent of a fireworks finale.

"Quite surprisingly, the finale came first. The fireworks ran backward. It's not exactly what would have been predicted," said Bruce Margon, associate director for science at the Space Telescope Science Institute in Baltimore, which operates the Hubble Space Telescope.

Exactly what happened in the hundreds of millions of years after the Big Bang remains a mystery. The universe has expanded since its creation.

Most astronomers had assumed that answers to the mystery would not come for at least a decade--until the next generation of space telescopes are up and able to detect the faint traces of light from the earliest of stars. Astronomer Ken Lanzetta was unwilling to wait.

Lanzetta, an astronomer at the State University of New York at Stony Brook, based his theory on a new analysis of pictures of a nearly two-week-long exposure of a patch of seemingly empty sky known as the Hubble Deep Field. With that long exposure time, Hubble's camera was able to pick up faint traces of light from galaxies that existed when the universe was less than 1 billion years old.

"They are faint little blobs of light . . . barely discovered by the Hubble telescope even with all the stops pulled out," Lanzetta said.

Lanzetta and his colleagues suspected the galaxies were much more luminous. In the photo, they merely appeared faint because they were so far away, he hypothesized. His team reanalyzed the images, making use of how the spectrum of light coming from galaxies is shifted depending on their distance from Earth-based observers. The new analysis suggests that the galaxies are indeed much brighter than they appear.

"The light [they give off] is just too faint and has been missed by all previous measurements," he said.

All that light, Lanzetta believes, means that multitudes of stars must have been created very early on, before the universe was even a billion years old. "Our results indicate the early universe contained far more light and far more stars than earlier believed," he said.

The results, announced Tuesday at NASA headquarters in Washington, were just beginning to circulate among astronomers at their annual meeting. The findings are controversial among astronomers because they rely on inferences made about light that was not actually seen and estimated corrections to the amount of light that may be off.

"Many people don't think that so much light is missing from the early universe," said Richard Ellis, a cosmologist at Caltech who is searching for the universe's "first light" and is for now sticking to theories that suggest most stars formed after the universe was at least a billion years old.

"Even if there is a bit of light missing, it's not going to overthrow current thinking on the universe," he said.

A Jet Propulsion Laboratory astronomer who helps run the camera on Hubble that took the photograph also wanted more proof. "The observation technique sounds relatively reasonable, but they are making big claims, so they'll have to be verified," said Karl Stapelfeldt, who works on Hubble's Wide-Field Planetary Camera, which was built at JPL in Pasadena.

Most astronomers think the findings cannot be absolutely confirmed until more powerful telescopes capture the light that Lanzetta believes is out there. Margon, however, praised Lanzetta's analysis. The work succeeded in "teasing out an incredibly subtle result from what is really just little fuzz balls," he said.

The results are so new that even astronomers sold on the results Tuesday could not say how they might alter theories on the evolution of the universe and questions over whether stars were created before galaxies or vice versa.

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