Article Posted on : - Dec 07, 2011

An artist's concept of the fastest rotating star found to date.

PARIS (BNS): A "runaway star" rotating at breakneck speed has been spotted by an international team of astronomers and is believed to be the fastest rotating star discovered to date.

The star, VFTS 102, is found by ESO's Very Large Telescope in our nearby galaxy, the Large Magellanic Cloud about 160000 light-years away from Earth.

The star is rotating at more than two million kilometres per hour -- over three hundred times faster than the Sun and very close to the point at which it would be torn apart due to centrifugal forces.

The astronomers also found that the star, which is around 25 times the mass of the Sun and about one hundred thousand times brighter, was moving through space at a significantly different speed from its neighbours.

"The remarkable rotation speed and the unusual motion compared to the surrounding stars led us to wonder if this star had had an unusual early life," said Philip Dufton, lead author of the paper presenting the results.

This difference in speed could imply that VFTS 102 is a runaway star -- a star that has been ejected from a double star system after its companion exploded as a supernova, say the researchers.

This idea is further supported by two further clues: a pulsar and an associated supernova remnant in the star's vicinity.

A possible theory the astronomers' team gives for VFTS 102 is that the star might have started life as one component of a binary star system. If the two stars were close, gas from the companion could have streamed over and in the process the star would have spun faster and faster.

This would explain one unusual fact -- why VFTS 102 is rotating so fast.

After a short lifetime of about ten million years, the massive companion would have exploded as a supernova -- which could explain the characteristic gas cloud known as a supernova remnant found nearby.

The explosion would also have led to the ejection of the star and could explain the third anomaly -- the difference between its speed and that of other stars in the region.

As it collapsed, the massive companion would have turned into the pulsar that is observed today, and which completes the solution to the puzzle.

Though the team of researchers is not sure that this is exactly what happened, Dufton concludes "This is a compelling story because it explains each of the unusual features that we've seen. This star is certainly showing us unexpected sides of the short, but dramatic lives of the heaviest stars."