Archaeology is going to the heavens to find the origin of stars

A spiral galaxy on a star field background. The formation and evolution of spiral galaxies could be revealed by the GALAH survey.

Archaeology is going to the stars to help solve one of the fundamental mysteries of astronomy — how the more than 100 billion galaxies in the universe formed and evolved.

“Now we are going back to the very beginning of the Milky Way and using the astronomical equivalent of fossils to understand how our galaxy and those beyond it came about,” says Dr Gayandhi De Silva, from the University of Sydney’s School of Physics.

“Until now if we wanted to understand how the beautiful star clusters inside the Milky Way formed, or the spectacular spiral galaxies beyond it, we were limited to studying, at the very most, a few hundred stars from near the sun.”

The scientists will be using the GALAH survey, an international five-year project led by Australia, involving 70 astronomers from 17 institutions in eight countries. GALAH probes ten times further into the galaxy and is the first attempt to survey a million stars to create a dataset which will be used by astronomers worldwide for decades to come.

: An artist’s impression of light from a distant star entering the Anglo-Australian telescope at Siding Spring Observatory. Image: Amanda Bauer.

It is led by Dr Gayandhi De Silva and Professor Joss Bland-Hawthorn from the University of Sydney and Professor Ken Freeman from the Australian National University.

Dr De Silva is the lead author on a Royal Astronomical Society Journal article outlining the background and goals of the survey).

GALAH refers to Galactic Archaeology with HERMES. HERMES is the new $13 million instrument on the Anglo-Australian Telescope at Siding Spring Observatory near Coonabarabran, New South Wales, and can analyse light from up to 400 stars or galaxies at the same time. GALAH is the main purpose for which HERMES was built.

“Galactic archaeology means we dig down into the chemical origin of stars to find out where they came from and how they formed,” says Professor Bland-Hawthorn who, together with Professor Freeman, co-founded the discipline in 2002.

The scientists will use HERMES to measure up to 29 chemicals in the stars, as well as the stars’ temperature, gravity and velocity to inform their understanding.

“Instead of only relying on what we can discover from their current positions GALAH allows us to trace the stars’ origins – including the origin of our sun – and map their growth and movement through time and space,” Dr De Silva says.

“Our archaeology of space is a new era in astronomy and the knowledge gained promises to be every bit as exciting and important as anything discovered on Earth.”

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