Published on November 9th, 2012 | by James Ayre0
Star Formation In The Universe Is Now Only 1/30th Of What It Was At Its Peak
November 9th, 2012 by James Ayre
The team, led by David Sobral of the University of Leiden in the Netherlands, publish their results
The currently accepted theory of the Universe formed estimates that stars started forming around 13.4 billion years ago, that’s about 300 million years after the Big Bang is thought to have occurred. The majority of these first stars are theorized to have been enormous by the standards of today, containing hundreds of times more mass than the Sun. But these aged very fast, burning quickly through their fuel, and exploding as supernovae after only a few million years. Stars with lower masses generally live much longer than that.
The majority of the gas and dust that is released by supernovae then reforms into new 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. Unveiling the history of star formation across cosmic time is fundamental to understanding how galaxies form and evolve.”
For the new study, the researchers used the UK Infrared Telescope (UKIRT), the Very Large Telescope (VLT) and the Subaru telescope to do “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, so we can really understand how conditions change over time.”
“By looking at the light from clouds of gas and dust in these galaxies where stars are forming, the team are able to assess the rate at which stars are being born. They find that the production of stars in the universe as a whole has been continuously declining over the last 11 billion years, being 30 times lower today than at its likely peak, 11 billion years ago.”
Dr Sobral comments: “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!”
“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. 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. The future may seem rather dark, but we’re actually quite lucky to be living in a healthy, star-forming galaxy which is going to be a strong contributor to the new stars that will form.”
“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?”
The new research was just published in the journal Monthly Notices of the Royal Astronomical Society.
Source: Royal Astronomical Soceity
Image Credits: D. Sobral
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