Astronomers to track migrating stars with ’genetic markers’

Some people are born, live and die in the one village. Others cross the world to new homes. Stars do the same. Our Galaxy is a melting-pot of stars from different places.

A team of 55 astronomers from 10 countries is today [Friday 10 February] releasing data on 25 000 stars to the rest of the astronomical community — data that will help sort the travellers from the stay-at-homes, and unravel the history of the Galaxy.

“Some stars were formed in our Galaxy. Others were originally in small galaxies that have been swallowed by ours. By measuring their chemistry, and tracing their speeds and directions, we can learn which stars came from where,” said Dr Quentin Parker of Macquarie University and the Anglo-Australian Observatory, and head of the RAVE Data Management Team.

“It’s like tracing how people have migrated all over the world, using genetic markers.”

The research program, called RAVE (Radial Velocity Experiment) has collected the chemical compositions and velocities (speeds) of about 90 000 stars to date — the 25 000 being released today and other 65 000 still being rigorously checked.

Even these first 25 000 measurements are more than all the stellar velocities measured in the previous century.

Ultimately the astronomers plan to build a database of a million individual stars.

To do this over just a few years they need to measure lots of stars simultaneously. And for that they’ve turned to the Anglo-Australian Observatory’s 1.2-m UK Schmidt telescope at Siding Spring Observatory in central New South Wales, Australia.

“The Schmidt is a really wide-eyed telescope. It can see a patch of sky six degrees across — that’s like 12 full moons lined up in a row,” said Professor Fred Watson, RAVE Project Manager and Astronomer-in-Charge at the Anglo-Australian Telescope.

The telescope is coupled with the AAO’s ‘six-degree field’ (6dF) spectrograph, which analyses the stars’ light. The 6dF system can capture the spectra of up to 150 stars simultaneously. From the spectra the astronomers determine the stars’ velocities, chemical composition, temperature and gravitational strength.

The system can measure up to 700 stars a night.

The data release is being announced at the Local Group Cosmology meeting in Aspen, Colorado, by the leader of the RAVE collaboration, Professor Matthias Steinmetz of the Astrophysical Institute Potsdam in Germany.

Members of the RAVE team come from Australia, Canada, France, Germany, Italy, The Netherlands, Slovenia, Switzerland, the UK and the USA.