A second look at a group of massive young galaxies 11 billion light-years away has revealed these juvenile giants in the throes of a celestial baby boom, birthing stars at an astonishing scale and rate.

The new glimpse of such a productive early universe -- seen as it looked 3 billion years after the Big Bang -- may change the way scientists think about star formation.

The new data came courtesy of the European Space Agency's Herschel Space Observatory, an orbiting satellite equipped with the largest mirror ever built for a space telescope.

"These measurements have revealed the new population of galaxies to be hotter than expected, due to stars forming far much more rapidly than we previously believed," researcher Scott Chapman of the Institute of Astronomy in Cambridge, England, said in a release.

Previous observations had revealed the young galaxies, but their light in the visible spectrum was very faint, obscured by clouds of gas and dust within which the newly formed stars were being born. [See an illustration of the stellar baby boom]

This cosmic dust is much brighter at the longer, far-infrared wavelengths of light observed by the Herschel satellite.

"With the data we had before, we couldn't tell exactly where the infrared light from these galaxies comes from," said Rob Ivison, a professor at the University of Edinburgh. But using the instruments aboard Herschel, Ivison said, "we can see that this is the signature of star formation."

The Herschel observations focused on about 70 galaxies in the constellation of Ursa Major. The data reveal spectacular rates of star formation, far higher than anything seen in the present-day universe, and indicate the young galaxies possess large reservoirs of gas that will power the star formation for hundreds of millions of years.

With the new discovery, the astronomers have provided a much more accurate census of some of the most extreme galaxies in the universe at the peak of their activity. [Top 10 Star Mysteries]

"It was amazing and surprising to see the observations uncover such a dramatic population of previously unseen galaxies," said Isaac Roseboom, a research fellow at the University of Sussex.

Future observations will investigate the details of the galaxies' power source and try to establish how they will develop once their intense bursts of activity come to an end.

The results are presented in a special edition of the journal Monthly Notices of the Royal Astronomical Society.

*   Top 10 Star Mysteries
  *   Video – The Herschel and Planck Missions
  *   Spectacular Nebulas in Deep Space

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