Astronomers have unlocked the 'DNA' of more than 340,000 stars, a discovery they say is a major boost to their quest to discover the ancient stars related to the sun.

The groundbreaking collection of chemical DNA from stars was hailed as huge breakthrough by the Australian-led team of astronomers, who spent hundreds of nights since 2014 examining starlight using high-tech equipment near Coonabarabran in NSW's central west.

One of the lead astronomers Dr Gayandhi De Silva, of the University of Sydney, said mapping the chemical makeup of individual stars reveals which ones were "born" at the same time - information which may shine new light on the mystery of the universe's evolution after the Big Bang 14 billion years ago.

"This data will enable such discoveries as the original star clusters of the galaxy, including the sun's birth cluster and solar siblings - there is no other dataset like this ever collected anywhere else in the world," he said on Wednesday.

Scientists estimate the sun formed 4.5 billion years ago and then became the centre of our solar system.

Like most stars, the sun is believed to have been "born" as part of a cluster of stars.

But while the sibling stars within individual clusters share the same chemical makeup, they are pulled apart and scattered across the galaxy.

To find which ones are related, astronomers examined light emitted from individual stars using the HERMES spectrograph at the Australian Astronomical Observatory's giant Anglo-Australian Telescope site at Coonabarabran.

The telescope tracks starlight and feeds it into the spectrograph, which splits the light into spectra, or the rainbow colours of visible light.

The astronomers examined the dark lines, or absorption lines, in the spectra to identify each star's chemical composition.

The study is part of the ongoing Galactic Archaeology survey, dubbed GALAH, which launched in 2013 with the aim of examining one million stars to help improve our understanding of how galaxies form and evolve.

Professor Martin Asplund, of ANU's Research School of Astronomy and Astrophysics, said while GALAH had identified some stars that were related, the search continues for the sun's siblings and possibly its twin.

"We know that most stars are born together like twins within a cluster itself so it's quite likely the sun has a twin and it may have been flung out over time," he told AAP.

"We know that the sun doesn't orbit another star but the twin may have been lost and is lurking somewhere else in the galaxy."

The GALAH team is waiting to compare its data with fresh information due on April 25 from the European Gaia satellite, which has been examining the Milky way's 1.6 billion stars.