Astronomers are closing in on one of the most enigmatic periods of cosmic historythe era when stars first lit up the darkness of space. A recent analysis of a Hubble Space Telescope image hinted that massive stars were born en masse in a giant conflagration a few hundred million years after the Big Bang. Observations from the 2MASS ground-based map of the infrared sky confirm the early fireworks. Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and his colleagues processed 2MASS data to filter out nearby stars and galaxies. The remaining glow, produced by galaxies that formed when the universe was less than a billion years old, was two to three times brighter than expected. "It means galaxies were forming stars at a gigantic rate," he says, more than 30 times faster than in our galaxy today.
Astrophysicist Michael Norman of the University of California at San Diego and his colleagues created a supercomputer simulation to peer even deeper in time. Their model indicates stars started forming 100 million years after the Big Bang, much earlier than previous estimates. Those pioneer stars, 100 times more massive than our sun, condensed from hydrogen and helium gas, "pristine stuff from the Big Bang," Norman says. Such huge stars would have lived a few million years before exploding as supernovas. But during that brief time, they synthesized the first heavy elementsthe carbon, nitrogen, calcium, and other materials that eventually found their way into planets and life. Until now, cosmologists had little information about when and how the earliest stars formed. "We're shedding light on an epoch that hadn't received much attention. So for now, we're the dogma," Norman says.