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Our Galaxy is all a-flutter

29 October 2013

Our Galaxy is fluttering like a flag, with chaotic wave patterns running through it.

That’s one thing astronomers have learned from the RAVE (Radial Velocity Experiment) survey, carried out over the past 10 years with the UK Schmidt Telescope run by the Australian Astronomical Observatory at Siding Spring Observatory in northwest NSW.

“The RAVE survey outcomes show the value of international collaboration by Australian scientists to shed light and understanding on our place in the universe,” Industry Minister Ian Macfarlane said.

“This has been a major long-term project, built around leading edge robotic technology developed by scientists and engineers at the Australian Astronomical Observatory that allows more than 100 stars to be studied simultaneously.”

Astronomers are analysing data in detail on the brightness, colour, distance and movement of almost half a million stars gathered by RAVE from 2003 to earlier this year.

Dr Mary Williams of the Leibniz Institute for Astrophysics Potsdam (AIP) in Germany led the present study, which covered a region 6,500 light-years above and below the plane of our Galaxy, and from 20,000 to 30,000 light-years out from the Galactic Centre.

The research team measured the distances and velocities of stars of similar brightness.

“We see the stars moving up and down like corks on water when a wave goes through,” said Australian National University’s Professor Ken Freeman, the RAVE Project Scientist.

“When we combine the RAVE data with data from other surveys we see that the Galaxy’s stars are moving in quite a complex way.”

There could be several causes, Professor Freeman said, including the effects of the Galaxy’s central “bar” of stars, and its spiral arms.

“Our Galaxy has swallowed other small galaxies, and this could have disturbed the stars,” he said.

"A lump of dark matter could have gone through the disk of the Galaxy, or a cloud of hydrogen gas could have fallen into it."

Countries participating in RAVE are Australia, Canada, Germany, France, Italy, the Netherlands, Slovenia, the UK and the USA.

The Australian Astronomical Observatory is our national optical observatory, and is part of the Commonwealth Department of Industry. It operates the 3.9-m Anglo-Australian Telescope and the 1.2-m UK Schmidt Telescope at Siding Spring.

More information:
Professor Fred Watson, Australian Astronomical Observatory, M: +61 420 897 860 Fred.Watson [at] aao.gov.au 
Professor Ken Freeman, Australian National University (Canberra, Australia), T:+61 2 6125 0264 M: +61 402 134 289 Kenneth.Freeman [at] anu.edu.au 
Dr Mary Williams, Leibniz Astrophysical Institute Potsdam, Germany, M: +49 1767 7585 354 mary [at] aip.de

Media contact: Minister Macfarlane's office 02 6277 7070