The first stars in the universe died long before scientists could get a look at them. Today, billions of years after the last of these first stars burned out, Alliance researchers are tracking them down.

Millions of years after the Big Bang, and the universe wasn't much of a party.

It started out great. An incredible explosion occurred - scientists still don't know why or even what forces were at work - and space, time, and all the matter that will ever be in the universe were born. Within the first second, protons, neutrons, and electrons formed. Within three minutes, protons and neutrons combined into the nuclei of what would eventually be hydrogen and helium atoms. The joint, as they say, was jumpin'.


Michael Norman
University of Illinois
at Urbana-Champaign 		But then things cooled off - literally. The universe started at about 1032 kelvin but was down to about one billion kelvin in three minutes. The next major "signal event" in the formation of the universe, however, wouldn't come for another 300,000 years, when the temperature reached 3,000 kelvin and electrons began orbiting those nuclei to form atomic hydrogen.


From there, the party continued to cool off, eventually reaching a few degrees kelvin, and the matter of the universe slowly began to condense. As density increased, small amounts of atomic hydrogen combined to form molecular hydrogen, about one molecule for every million atoms.

Hydrogen is important, essential even, but most of us associate the universe with bigger things, like stars. So when did the first stars form? How big were they and what were they like? Theoretical answers to those questions vary wildly among researchers. Simulations of first star formations, recently created by Alliance cosmology team member Michael Norman and his colleagues Thomas Abel and Greg Bryan, may settle these grand debates once and for all.



Access Online | Posted 11-16-1999

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