Peletier's researchers studied the center of 20 spiral galaxies that have large bulges. They concluded that elliptical bulges of stars formed over a relatively brief period very early in the young universe, either through the collapse of a single cloud of hydrogen or the merger of primeval star clusters. The groups used Hubble telescope to study more than 200 neighboring galaxies, out to a distance of 100 million light years. A light year is the distance light travels in a year. Using visible light and infrared cameras, they were able to determine the stars' true colors.
Older stars tend to be redder, but space dust can interfere with color perception from Earth.
The Hubble space telescope permitted the researchers to look past that dust. Peletier's report is scheduled for publication in Monthly Notices of the Royal Astronomical Society and Carollo's work will appear in Astrophysical Journal. New pictures from NASA's Hubble Space Telescope are giving astronomers their first clues about why galaxies look the way they do. Those stars are chemically rich in elements such as oxygen, magnesium and titanium, suggesting they were formed by supernovae, the violent explosions of other, earlier stars. The whole bulge is bathed in a disc-like cloud of dust and gas that is funneled by gravity into the galaxy's center.