An international team of astronomers using Mauna Kea's twin Keck telescopes has peered farther back in time than anyone ever has — 13 billion years — to collect information about the universe when it was very young.

Using natural "gravitational lenses" in space, the researchers have seen the most distant objects ever spotted, believed to be galaxies in which stars were actively forming.

Since no existing telescope is powerful enough to see these events, the astronomy team employed massive galaxies whose gravity is so great that they magnify objects behind them.

These galaxies themselves are more than 2 billion light years from our own. (A light year is the distance traveled by light in a year's time, or about 5.9 trillion miles.)

Viewing radiation amplified by these galaxies, the researchers believe they have spotted features that significantly add to the knowledge of the early universe.

"Gravitational lensing is the magnification of distant sources by foreground structures. ... We have located six star-forming galaxies seen at unprecedented distances, corresponding to a time when the universe was only 500 million years old, or less that 4 percent of its present age," said team leader Richard Ellis of the California Institute of Technology.

Those objects were so far away that astronomers calculated the light collected by the Keck telescope mirrors left the galaxies 13 billion years ago. The universe began, according to current astronomy theory, with the Big Bang, which took place about 13.5 billion years ago.

The latest work shows that stars — a lot of them — were actively being formed 500 million years after the Big Bang.

"We only surveyed a tiny area ... so it's a bit like looking through the eye of a hypodermic needle. If we find anything, it suggests either we were incredibly lucky or there is a dominant population of early sources out there. We conclude the latter," Ellis said by e-mail from London.

"The objects we see are very young, with very low mass, but we are seeing the characteristic signature of stars forming. These are galaxies which are undergoing a burst of star formation," said Caltech graduate student Dan Stark.

COSMIC DAWN

Astronomers believe that about 300,000 years after the Big Bang, there were no stars — a period they refer to as the Dark Ages. At some point, stars and galaxies began forming and emitting light — an undetermined time some call the "cosmic dawn."

What's not yet clear is whether the early stars seen by Ellis' team are among the very first stars to form. They may not be, Stark said.

"Were these the first generation of star-forming objects? Is this the cosmic dawn? We don't have enough information to say. I wouldn't think of these objects as truly primordial. There should be objects earlier in the history of the universe," he said.

But it likely will be several years before anyone can know for sure. Astronomy will need much more powerful telescopes to see any farther back in time. Plans for two such telescopes are in the works. One is the James Webb Space Telescope, scheduled for launch in 2013. The other is the land-based Thirty Meter Telescope, which organizers hope to open in 2015.

The astronomy community believes that if you look with a big enough telescope, you should find something, Stark said.

"The light is out there, we think," but it is extremely faint, he said.

FINDINGS SUPPORTED

The researchers concede there may be skeptics who suggest their galaxies are not as old as they say. But preliminary findings from another group of astronomers who are using the Hubble and Spitzer space telescopes support the conclusions of the research done with Mauna Kea's Keck telescopes, they said. That second group is led by Caltech astronomer Johan Richard.

The Ellis team did some preliminary work on the Keck I telescope, and spotted the ancient galaxies on the Keck II.

"When we began this survey, there was naturally some risk in spending so much observing time hoping we'd find something. We might, quite honestly, have found nothing at all. But the universe has cooperated and we're very excited at this glimpse of the early phases of its history," Ellis said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.