Milky Way has four spiral arms: Study

Last Updated: Wednesday, December 18, 2013 - 12:48

Washington: Researchers have said that a 12-year-old study of massive stars has reaffirmed that Milky Way has four spiral arms.

Co-author Professor Melvin Hoare, a member of the RMS Survey Team in the School of Physics and Astronomy at the University of Leeds, said that studying Milky Way`s structure gives them a unique opportunity to understand how a very typical spiral galaxy works in terms of where stars are born and why.

In the 1950s astronomers used radio telescopes to map our galaxy. Their observations focused on clouds of gas in the Milky Way in which new stars are born, revealing four major arms.

NASA`s Spitzer Space Telescope, on the other hand, scoured the galaxy for infrared light emitted by stars. It was announced in 2008 that Spitzer had found about 110 million stars, but only evidence of two spiral arms.

The astronomers behind the new study used several radio telescopes in Australia, USA, and China to individually observe about 1,650 massive stars that had been identified by the RMS Survey.

From their observations, the distances and luminosities of the massive stars were calculated, revealing a distribution across four spiral arms.

"It isn`t a case of our results being right and those from Spitzer`s data being wrong-both surveys were looking for different things," said Professor Hoare. "Spitzer only sees much cooler, lower mass stars-stars like our Sun-which are much more numerous than the massive stars that we were targeting."

The research has been published online in Monthly Notices of the Royal Astronomical Society (MNRAS).


First Published: Wednesday, December 18, 2013 - 12:36

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