Big Bang Ripples Formed Universe's First Stars

July 31, 2008

Ripples in the early universe following the big bang 13.7 billion years ago caused gases to coalesce into the luminous seeds of the first stars, a new computer simulation reveals.

Such stellar embryos, or protostars, were the universe's first astronomical objects and its first sources of light.

Previous telescope observations have shown that very distant—and thus very old—cosmic objects contain heavy elements such as carbon and iron, which are formed only by the nuclear reactions inside full-grown stars.

This suggests that massive stars must have existed even earlier in the universe's history than telescopes can see. Until now, the earliest stages of primordial star formation had not been modeled in detail.

"Previous works probed up to only intermediate stages where only gas blobs or dark matter clumps are formed," said lead study author Naoki Yoshida of Nagoya University in Japan.

The new research brings astronomers a step closer to simulating the entire birth of an early star all the way up to nuclear ignition.

Understanding such processes is vital to figuring out how subsequent stars developed and seeded the cosmos with the elements that eventually gave rise to life.

(Related: "Dark Matter May Have Powered Universe's First Stars" [December 6, 2007].)

"If we want to understand how things came about and why they look the way they do now, we have to go back in time and understand how stars looked when they first began to form," said study co-author Lars Hernquist of the Harvard-Smithsonian Center for Astrophysics (CfA).

Simple Recipe

The first adult stars were bright, short-lived behemoths that ended the so-called cosmic dark ages—a 200-million-year period beginning shortly after the big bang when there was no visible light.

When some of these first stars died in explosive events called supernovae, they bequeathed a valuable inheritance of heavy elements to the rest of the universe.

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