A composite image of a molecular cloud used as a model to determine how stars are formed.
Hot off the astronomical press: the star census is complete. An international team of astronomers has conducted the first, comprehensive survey of stellar formation in the universe. The undertaking was ten times bigger than any star formation study before it, and confirmed that the rate of star formation has slowed significantly over time. But the researchers upped the stakes with this one by finding that the universe is now almost out of star-making materials.
Scientists used three massive telescopes for their observations, including the VLT (Very Large Telescope) in Chile, and two in Hawaii: the United Kingdom Infrared Telescope and the Subaru. Through these telescopes the scientists observed hydrogen alpha emissions. They essentially took snapshots of star-forming galaxies 4, 7, 9 and 11 billion years ago, which they assembled into a sort of panoramic history of star formation in the universe.
The researchers found that the rate of star formation in the distant, early universe was much greater than in the closer, more recently formed universe. In fact, based on the extrapolation of their results, published in the Monthly Notices of the Royal Astronomical Society, 95 percent of the universe’s stars have already been formed, half of them in a flurry between 9 and 11 billion years ago. The remaining half have come into existence more gradually since then.
If this rate of formation continues to decline, the astronomers predict that the universe will only churn out another five percent of its current star population before halting production.
Image courtesy of NASA.