Star survey sheds light on galaxy origins

Star survey sheds light on galaxy origins

10 April 2013

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Australia — ASTRONOMERS using a telescope that escaped a bushfire in January have completed a survey shedding light on stars’ origins and how galaxies grow by gobbling up their neighbours.

A research team from nine countries has been engaged in the 10-year Radial Velocity Experiment (RAVE), using data gathered at the Siding Spring Observatory near Coonabarabran in NSW’s northwest.

The observatory escaped destruction on January 13 after a massive bushfire swept past, burning down a lodge and other outbuildings.

Project manager Fred Watson of the Australian Astronomical Observatory says the observing side of the project was due to end in February, but the fire delayed its completion as observation time was lost.

The project aimed to find out where stars were born in our galaxy and how it evolved in its 12 or so billion years, Professor Watson told AAP on Wednesday.

“In particular we’re looking for evidence that our galaxy has grown by absorbing other galaxies; kind of galactic cannibalism.

“Certainly evidence for that has come from the RAVE survey.”

RAVE revealed a dwarf galaxy swallowed and shredded by our own galaxy.

Prof Watson said stars with a common speed tend to have a common origin so such a stream of stars found in the sun’s neighbourhood probably came from an older galaxy absorbed by ours.

He said that since 2003, data had been collected on almost half a million stars, using robots to precisely position optical fibres to capture their light.

A spectograph then spread out the wavelengths of the light, with the colours telling astronomers about the chemical elements a star contained and how it was moving.

From that, the astronomers could work out how old the stars were, where they came from and how they were related.

RAVE also enabled our galaxy to be weighed, coming in at about 1.6 trillion times the mass of the sun.

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