Hubble Peers Deep Into Space - And Time

Powerful New Camera Brings Celestial Events Into Focus

December 13, 2009|By Frank D. Roylance | Frank D. Roylance ,

Pushing the Hubble Space Telescope's newest camera to its limits, astronomers say they have captured images of some of the most distant galaxies ever seen - more than 13 billion light years away.

Amid a swarm of oddly shaped objects in the photograph are some dim, reddish spots that the scientists believe to be some of the earliest galaxies ever formed, seen as they appeared just 600 million years after the Big Bang that marked the beginning of the universe.

"Preliminary indications are that we are indeed seeing some galaxies at [greater distances] than we saw previously," said Massimo Stiavelli, an astronomer at the Space Telescope Science Institute in Baltimore. He is a co-investigator on the latest observations, and a member of the team that developed the telescope's powerful new Wide Field Camera 3.

His team is "seeing some of our early hopes confirmed," he said after the first image was released this week. "I think the instrument works very well. There are always teething problems, but they are very minor compared to other instruments. It's been a pretty impressive success, I would say."

Scientists who study the beginnings of the universe have long pushed for more powerful cameras and telescopes to enable them to see ever deeper into the cosmos - and thus farther back in time.

That, they say, will help them piece together the sequence of events that led to the birth of the first stars, the assembly of the first galaxies and the evolution of those galaxies into the vast spirals and glowing ellipticals visible much closer to us in time and space today.

"Essentially, you have an archaeological record there," said Henry C. Ferguson, another astronomer at the institute who is conducting separate studies of the earliest galaxies.

"You're ... trying to piece together a statistical picture of each slice in time; to see what the galaxies look like, estimate how many stars are in them, how much dust is in them, and their ages," he said. "You try to build a picture of how we got from tiny pieces of galaxies to the big galaxies we see today."

Ferguson called the early results of Stiavelli's project "spectacular."

Astronauts installed the new Wide Field Camera 3 in May. Unlike previous instruments used to probe the deepest reaches of the universe in visible light, the new WFC3 is tuned to the near-infrared wavelengths.

It's a crucial advance, astronomers say, because, as the universe has expanded since the Big Bang, the waves of visible light from the first stars have been stretched - like wire Slinky toys - as they streamed toward Earth. And that has shifted them from shorter, visible or "optical" wavelengths to longer infrared wavelengths invisible to instruments built to see in the same range as the human eye.

"At a certain point, the galaxies are so red-shifted they disappear from the optical," Ferguson said. "Hubble previously would not have seen them."

The new camera not only sees galaxies too far, too dim and too red-shifted to show up in previous images, it can also see them across a much broader field of view - collecting data on far more of these ultra-distant galaxies at once, and doing it 30 times faster.

Of course, "broad" is a relative term to astronomers. Ferguson said the new image encompasses a seemingly empty patch of sky about the size of a grain of sand held at arm's length.

Stiavelli's team began its observations in late August, as Hubble was still being checked out and calibrated in the wake of the May repairs and upgrades. They made exposures totaling 173,000 seconds over four days.

Then, they began a period of data processing. Typically, computer programs first rid the images of "artifacts," such as those caused by solar radiation, Ferguson said. Then the software sorts through all the galaxies and classifies them by size, color and brightness, looking for the most interesting, most red-shifted ones.

The astronomers then step in "and decide whether you believe what the computer has found," Ferguson said. Light from those galaxies is analyzed to determine how distant they really are, and the physical properties revealed by their light spectra.

That could take years, but even as they continue working to process additional data and improve its quality, Stiavelli said, "the data is already good enough to begin scientific analysis," he said.

As good as Hubble has been at probing the farthest depths of space and time, Stiavelli and his competitors are eagerly awaiting the James Webb Space Telescope, a giant infrared observatory scheduled for launch in 2014.

"With Hubble, we are acting as a pathfinder," said Stiavelli, who is also on the institute's Webb telescope team. "Some of the galaxies we are finding today will be studied in great detail by James Webb. We are a bridge to the future."

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