D
docm
Guest
http://www.physorg.com/news122034732.html<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p><b>First stars might have been powered by dark matter<br /><br /><i>For a long time, scientists have assumed that the very first stars were powered by fusion, in processes similar to what goes on in present day stars. But a new theory is emerging to challenge that view. “The first stars were different in a lot of ways,” Katherine Freese, a theoretical physicist at the University of Michigan, tells PhysOrg.com.</i></b><br /><br /> Freese, along with Douglas Spolyar at the Unversity of California, Santa Cruz and Paolo Gondolo at the University of Utah in Salt Lake City, posit that dark matter annihilation was the source of energy that powered the earliest stars, formed about the time the universe was between 100 and 200 million years old.<br /><br />If they are right, some of what we know about stellar formation – and the formation of the universe itself – could be called into question. Their work appears in Physical Review Letters with the title “Dark Matter and the First Stars: A New Phase of Stellar Evolution.”<br /><br />“Annihilation means that matter goes into something else,” Freese explains. She says that everything has a partner opposite – matter and anti-matter, electrons and positrons. When these opposites meet, their identity is lost and the energy goes elsewhere. “Dark matter particles are their own anti. When they meet, one-third of the energy goes into neutrinos, which escape, one-third goes into photons and the last third goes into electrons and positrons.” <br /><br /><font color="yellow"><b>“In order for a star to form, in order for its matter to collapse into a dense object, it has to be able to cool off,” Freese continues. “We noticed that in the first stars something was competing with the cooling. The stars couldn’t collapse down small enough to get fusion going. But they were still</b></font></p></blockquote> <div class="Discussion_UserSignature"> </div>