USATODAY  • Cars • Jobs • Franchise • Business Opportunities • Travel • Photos • Real Estate • Tickets • More
Posted 1/5/2004 9:07 PM
Today's Top News Stories
Add headlines to your Web site
E-Mail Newsletters

New beginnings for old galaxies
ATLANTA — The discovery of old galaxies formed when the universe was young has astronomers rethinking the origins of these vast islands of stars.

Galaxies such as our own Milky Way — a spiral whirl of perhaps 200 billion stars, including the sun — come in a variety of shapes and sizes. The most common are elliptical ones, football-shaped balls of stars that include the largest and oldest galaxies.

Over the past two decades, many astronomers have come to see these giant ellipticals as the product of mergers between smaller spiral galaxies that play out over billions of years.

Understanding how galaxies form can help scientists answer many big questions, from why Earth is where it is today to how the Big Bang's explosive force shaped the universe.

But the results of a survey of more than 300 distant galaxies challenge certain assumptions about the formation of giant galaxies. The survey of galaxies that existed when the universe was from 3 billion to 6 billion years old was presented here Monday at the American Astronomical Society by the Gemini "Deep Deep" Survey team.

"Our big result is that massive galaxies seem to be forming surprisingly soon after the Big Bang," says co-leader Roberto Abraham of the University of Toronto.

"We should be seeing fewer of them further back in time, but we don't."

The researchers found by telescope that about 19% of the galaxies surveyed are giant ellipticals already filled with aging red stars, says team astronomer Sandra Savaglio of Johns Hopkins University.

That implies the galaxies formed about 12 billion years ago, only a billion or so years after the Big Bang started the cosmos — and much earlier than first expected.

The idea that giant elliptical galaxies slowly built up over billions of years has been under siege recently in results from the Hubble Space Telescope and elsewhere, but the survey results "really give it a strong push aside," says astronomer David Koo of the University of California-Santa Cruz, who was not a member of the GDDS team.

He expects results from NASA's Spitzer infrared space telescope to provide within the year an even better picture of how giant galaxies form, along with solving other mysteries about galaxies from all ages of the universe.

Scientists at the meeting also reported a pair of space oddities: the brightest star and the fastest-moving star yet seen.

Astronomer Steve Eikenberry of the University of Florida in Gainesville described perhaps the brightest and biggest star of all, LBV 1806-20. Up to 40 million times brighter than the sun, it outshines the "Pistol" star, the previous brightness record-holder spotted by Hubble in 1997.

Despite its brightness, LBV 1806-20 isn't visible from Earth. The star hides on the far side of the Milky Way, and dust blocks the view, except from infrared telescopes.

The fastest star, called PV Ceph, appears to have been a young star booted out of its home solar system by other nearby stars at speeds of about 40,000 mph, 10 to 20 times more than normal for a star. It was reported by astronomers Alyssa Gordon of the Harvard-Smithsonian Center for Astrophysics and Hector Arce of Caltech.