November 6, 2012
Rate Of Star Production On The Decline
Lee Rannals for redOrbit.com - Your Universe Online
Astronomers, writing in the journal Monthly Notices of the Royal Astronomical Society, have revealed that the rate of new stars in the Universe is dropping, which is a trend that could continue.
The team of astronomers from five different countries said the rate of formation of new stars is now only 1/30th of its peak.
The accepted model for evolution of the Universe suggests that stars began to form about 13.4 billion years ago. Many of these stars are thought to have been monstrous, and were probably hundreds of times more massive than our Sun.
These beastly stars aged quickly, and exploded as supernovae within a million years or so. Lower mass stars in contrast have much longer lives and last for billions of years.
Much of the dust and gas from stellar explosions was recycled to form newer generations of stars. Our Sun is thought to be a third generation star, and has a typical mass by today's standards.
In the new study, scientists used a few different telescopes to carry out the most complete survey ever made of star-forming galaxies. They collected around ten times the data of any previous effort.
By looking at the light around clouds of gas and dust in these galaxies where stars are forming, the team assessed the rate at which they were being born.
They found that the production of stars in the universe as a whole has been continuously dropping over the past 11 billion years, and is 30 times lower today than its peak.
"You might say that the universe has been suffering from a long, serious 'crisis': cosmic GDP output is now only 3% of what it used to be at the peak in star production," said David Sobral of the University of Leiden in the Netherlands, who led the research.
He said if the decline continues, then no more than 5 percent more stars will form over the remaining history of the cosmos.
"The research suggests that we live in a universe dominated by old stars. Half of these were born in the 'boom' that took place between 11 and 9 billion years ago and it took more than five times as long to produce the rest," Sobral said.
According to Sobral, we are lucky to be living in a healthy, star-forming galaxy which is going to be a strong contributor to new stars.
"Moreover, while these measurements provide a sharp picture of the decline of star-formation in the Universe, they also provide ideal samples to unveil an even more fundamental mystery which is yet to be solved: why?," Sobral concluded.