Universe's first stars spun at 1m mph

Posted by Emma Woollacott

The first stars in the universe may have spun at over a million miles per hour, astronomers at the Leibniz-Institut für Astrophysik Potsdam (AIP) and the Instituto Nazionale di Astrofisica (INAF) say.

Using data from ESO’s Very Large Telescope, they reanalyzed the spectra of a group of very old stars in the Galactic Bulge. And,  unexpectedly, they discovered elements usually thought to be produced only by stars of smaller masses.

But, says the team, fast-rotating massive stars would also be able to manufacture these elements. The eight stars, which would each been over eight times the mass of our sun, would have created the universe's first elements heavier than helium.

"Alternative scenarios cannot yet be discarded - but we show that if the first generations of massive stars were spinstars, this would offer a very elegant explanation to this puzzle,” says team member Cristina Chiappini.

The stars would have had to rotate with a surface speed of 1.1 million miles per hour, over four times as fast as most massive stars in the Milky Way; our own sun rotates at 4,400 mph.
 
These spinstars could have had a profound effect on the early universe. Their spinning could not only have led to an earlier-than-thought dispersal of heavy elements across the universe, but could also have increased the number of gamma ray bursts.

Fast rotation also affects other properties of a star, such as its colour, its lifetime and its luminosity, possibly explaining the reionization of the universe.

The team is now hoping to extend its simulations to test the theory further.