Universe may hold three times as many stars as thought

Posted by Kate Taylor

New observations have indicated that there are three times as many stars in the universe as previously believed.

Instruments at the Keck Observatory in Hawaii have detected the faint signature of red dwarfs in eight massive galaxies between about 50 million and 300 million light years away - and found that they are much more widespread than previously thought.

"No one knew how many of these stars there were," said Pieter van Dokkum, a Yale University astronomer who led the research. "Different theoretical models predicted a wide range of possibilities, so this answers a longstanding question about just how abundant these stars are."

The team discovered that there are about 20 times as many red dwarfs in these elliptical galaxies as in the Milky Way.

"We usually assume other galaxies look like our own. But this suggests other conditions are possible in other galaxies," says Charlie Conroy of the Harvard-Smithsonian Center for Astrophysics. "So this discovery could have a major impact on our understanding of galaxy formation and evolution."

For instance, Conroy said, galaxies may contain less dark matter than previous measurements of their masses might have indicated. Instead, the abundant red dwarfs could contribute more mass than realized.

As well as boosting the total number of stars in the universe, the discovery also increases the number of planets orbiting those stars -  in turn elevating the number of planets that might harbor life.

"There are possibly trillions of Earths orbiting these stars," van Dokkum said, adding that the red dwarfs they discovered, which are
typically more than 10 billion years old, have been around long enough for complex life to evolve. "It’s one reason why people are interested in this type of star."