Hubble finds galactic gems

The Hubble Space Telescope has found hundreds of celestial rubies that literally shed new light on how galaxies formed when the universe was young. The discovery of 500 ultra-distant, ultra-active galaxies demonstrates once again what a gem Hubble is - and today's successful conclusion of the Atlantis shuttle mission represents another step toward the space telescope's revival.

The galactic gold mine was found by analyzing imagery from the Hubble Ultra Deep Field as well as the Great Observatories Origins Deep Survey. "Ruby mine" might be a more apt term, because the signatures of the galaxies look like red jewels in the rough, sprinkled among the closer galaxies seen in the picture.

The finds are the focus of a paper to be published in the Nov. 20 issue of the Astrophysical Journal, as well as an image advisory issued today by the Space Telescope Science Institute as well as the European Space Agency's Hubble Information Center. This graphic from the institute and this cool ESA video help put the galaxies in proper perspective.

Although the fuzzy specks look ruby red in the Hubble pictures, that's just because the galaxies are so far away that their light has been redshifted by the expansion of the universe over billions of years. Their light signatures, or spectra, led astronomers to conclude that the galaxies date back to a time when the universe was less than 7 percent of its present age of 13.7 billion years - that is, about a billion years after the Big Bang.

When the researchers compensated for the redshift effect, they found that the galaxies would actually look very blue if you could see them at short range. In fact, they'd be blazing with the birth of hot, blue stars.

The characteristics of the light tell astronomers that these galaxies are predominantly dwarfs rather than giants. The study team's leader, Rychard Bouwens of the University of California at Santa Cruz, said this provides "evidence for galaxies building up from small pieces - merging together as predicted by the hierarchical theory of galaxy formation."

The spectral analysis also shows that starbirth was proceeding at a rate 10 times faster than what we see in galaxies that are closer in time and space. These stellar sparks could have fueled the reheating of hydrogen gas surrounding the first galaxies - a key transition time in the history of the universe, according to current theory.

"Seeing all these starburst galaxies provides evidence that there were enough galaxies 1 billion years after the Big Bang to finish reheating the universe," said Garth Illingworth of UC-

Santa Cruz. "It highlights a period of fundamental change in the universe, and we are seeing the galaxy population that brought about that change."

Other members of the research team include John Blakeslee of Washington State University and Marijn Franx of Leiden University in the Netherlands.

These observations were made possible by the installation of Hubble's Advanced Camera for Surveys during a 2002 space shuttle mission, and further revelations about the universe's early days could be made once Hubble gets its brand-new Wide Field Planetary Camera 3. That's just one of the instruments that would be added during a future space shuttle mission aimed at extending and bettering the space telescope's life.

And this is where Atlantis' mission plays a role: NASA mission managers wanted to make sure they wrapped up this successful flight before giving the go-ahead for the Hubble servicing mission.

As shuttle program manager Wayne Hale told me back in June, some preparations for that mission are already under way. With Atlantis' safe return, NASA is likely to be far more open about their planning for a Hubble visit in April 2008, if not earlier. Now let's hope that the telescope's guidance system and science instruments can hold out that long.

For more about Hubble and its gems, check out our space gallery as well as our interactive look at the space telescope's innards.