LONDON (TIP): Cosmic GDP crashes! Astronomers have discovered that the rate of formation of new stars in the Universe has drastically reduced to only 1/30th of its peak and that this decline is set to continue.
In the largest-of-its-kind study ever, scientists carried out the most complete survey ever made of star-forming galaxies at different distances, with around ten times the data of any previous effort.
With the range of distances, the time taken for the light to reach us means that we see identically selected galaxies at different periods in the history of the Universe.
By looking at the light from clouds of gas and dust in these galaxies where stars are forming, scientists led by David Sobral of the University of Leiden in the Netherlands, were able to assess the rate at which stars are being born.
They found that the production of stars in the Universe has been continuously declining over the last 11 billion years, being 30 times lower today than at its likely peak, 11 billion years ago.
“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!” Sobral said in a statement. “If the measured decline continues, then no more than 5% more stars will form over the remaining history of the cosmos, even if we wait forever,” he said.
The accepted model for the evolution of the Universe suggests that stars began to form about 13.4 billion years ago, or around three hundred million years after the Big Bang.
Many of these first stars are thought to have been monsters by today’s standards, and were probably hundreds of times more massive than our Sun. Much of the dust and gas from stellar explosions was (and still is) recycled to form newer and newer generations of stars.
Our Sun, for example, is thought to be a third generation star, and has a very typical mass by today’s standards. But regardless of their mass and properties, stars are key ingredients of galaxies like our own Milky Way. 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.