Originally created 01/17/97

New telescope images probe evolution of galaxies



TORONTO - Astronomers using the world's most powerful telescopes are beginning to see galaxies emerge from when the universe was just beginning to organize itself.

"We are beginning to look over the edge" into a time of early galaxy formation, Henry C. Ferguson of the Space Telescope Science Institute said Thursday at a meeting of the American Astronomical Society.

The data are coming from a long, penetrating look by the Hubble Space Telescope at a bit of sky of about the size of a grain of sand. By taking a long exposure, Ferguson said, the Hubble was able to gather light from more than 3,000 galaxies, each with about 10 billion stars.

Ferguson said the study is rather like a core sample of the heavens. It gathered light from sources in a shaft going out as far as the Hubble could look.

By analyzing the spectra of light from deep space images, astronomers are beginning to separate the stellar images that are relatively near the Earth from those that are much farther away.

In such astronomy images, distance equals time. The farther away an object is, the older it is and the nearer it is to the birth of the universe.

Ferguson said galaxies have been identified that originate from when the universe was about 1 billion to 2 billion years old, or 10-20 percent of its current age.

At the University of California, Santa Cruz, a team of astronomers used the powerful Keck Telescopes to analyze the deep field galaxies first captured by Hubble.

James Lowenthal of UC, Santa Cruz, said the analysis found that stars formed in the infant universe at about the same rate as in newer galaxies, such as the Milky Way, but that the star birth rate was slower than has been detected in the middle years of the universe.

This suggests, Lowenthal said, that star formation has waxed and waned over time.

The many different shapes of the early stellar formations, he said, suggest that early, small galaxies may have merged later to form the immense galaxies now seen in the heavens.

An analysis of the ancient starlight detected traces of carbon, oxygen, silicon and various metals. Since such matter is created in the birth and death of stars, the finding suggests that even at 1 billion to 2 billion years of age, the universe already had undergone many generations of stellar evolution.

Lowenthal said the Hubble and Keck studies have created a "bonanza" for astronomers seeking to understand how the universe's structure formed. Astronomers can now study more than 100 galaxies from that early age, which "was not true just a year ago," Lowenthal said.

Ferguson said the Hubble images have kept more than 100 astronomers busy and have resulted in publication of about 25 papers in scholarly journals.