ROANOKE TIMES
Copyright (c) 1996, Roanoke Times
DATE: Thursday, September 5, 1996 TAG: 9609050120
SECTION: NATIONAL/INTERNATIONAL PAGE: A-3 EDITION: METRO
SOURCE: The Boston Globe
Astronomers say new evidence suggests that galaxies were built up from smaller collections of stars that crashed together and merged, not, as widely believed, from the collapse of huge clouds of gas and dust.
The finding from the Hubble Space Telescope contradicts the account of galaxy formation found in most astronomy textbooks.
``The standard thing we teach in astronomy classes, mostly out of ignorance, is that galaxies form the way stars do - a cloud of gas gradually shrinks down,'' said Bruce Margon, an astronomer at the University of Washington. Now, he said Wednesday, we have ``some direct observational evidence that our textbook explanation may be wrong.''
The finding, made by a team of astronomers headed by Rogier Windhorst of Arizona State University, showed 18 small clumps of stars all about the same distance from Earth, a distance so great that their light is seen as it looked when the universe was less than one-sixth its present age. But they found no structures of that age that were as large as present-day galaxies. The discovery is detailed in Nature.
Stephen Maran, an astronomer at the Goddard Space Flight Center in Maryland, called it a ``truly remarkable finding'' of ``what may be the actual building blocks of galaxies.''
The astronomers trained the Hubble telescope on a tiny patch of sky - a region less that 1/10,000 the size of the full moon - for more than a day in order to collect the faint starlight from 11 billion light-years away. They found that patch of sky contains 18 of the small ``blobs'' of stars, Windhorst said. In a nearer region of space, a region of equivalent size might contain one or two much larger galaxies.
Windhorst said the blobs are so close together that their gravitational attraction inevitably will cause them to crash together and merge, forming some kind of larger structure similar to the galaxies seen in the universe today.
The evidence for galaxies' being created ``bottom up,'' or assembled from smaller pieces, rather than ``top down,'' from the collapse of an even larger structure, is not conclusive, said Anne Kinney, an astronomer at the Space Telescope Science Institute in Baltimore.
The huge clouds of gas and dust that would have collapsed to form galaxies according to the alternative theory would not be visible even with the power of the Hubble, she said, and it's possible that the collections of stars seen in the new pictures could represent an early stage of such a collapse. Nevertheless, she called the new pictures ``tremendously significant.''
LENGTH: Medium: 53 linesby CNB