First stars might have been invisible

SALT LAKE CITY, Dec. 3 (UPI) -- A U.S. study suggests the universe's first stars might have been invisible and much larger than our sun.

The study -- conducted by scientists from the Universities of Utah, Michigan, and California-Santa Cruz -- suggests the first stars contained so much dark matter that the fusion of hydrogen atoms into helium was delayed for millions of years. Dark matter is thought to make up 23 percent of the universe, although its existence has never been proved.

Both dark matter and dark energy have been proposed to account for observations that cannot be explained by the amount of visible matter and energy in the universe.

University of Utah Professor Paolo Gondolo, the study's first author, said gigantic stars might still exist, and could be detected from the gamma rays and other material ejected from them.

"They could last months. They could last 600 million years. Or they could last billions of years and still be around. We have to search for them," he said.

Gondolo said the research is the first to calculate how dark matter might influence the formation of the first stars.

The study is to appear in next month's issue of Physical Review Letters.