Hubble observations challenge conventional theories

Stephen Withers
Thursday, 03 May 2007 04:01

Science - Space

The discovery of three generations of stars in globular cluster by astronomers using the Hubble Space Telescope has brought conventional theories of star formation into question.

The European Southern Observatory has been studying globular cluster NGC 2808, one of the largest in the Milky Way.

"The generally accepted view is that all of its stars originated at the same time and place, from the same material and have co-evolved for billions of years," said team member Luigi Bedin of the European Southern Observatory in Garching, Germany. 

"This is the cornerstone on which much of the study of stellar populations has been built. So we were very surprised to find several distinct populations of stars in NGC 2808."

One possibility is that NGC 2808, being two or three times more massive than typical globular clusters, had sufficient gravity to retain the gases that would normally be blown into space during the first wave of star creation. Thus the raw materials remained for successive generations of stars.

An alternative is that NGC 2808 is not a true globular cluster, but a dwarf galaxy captured and stripped of most of its material by the Milky Way.