Astronomers study light from thousands of stars to find sun's birth-mates

The new Galactic Archaeology survey looks for matching ‘chemical DNA' in stars born together.

Astronomers searching for the sun’s lost siblings have mapped the “chemical DNA” of 350,000 stars.

They are looking for the chemical signatures of stars delivered into the universe together and then separated after birth.

Aeons ago, the sun was formed with many thousands of other stars in a “cluster” that was quickly pulled apart by gravity and scattered across our galaxy, the Milky Way.

Every star in the sun’s birth cluster will share the same chemical composition.

The Galactic Archaeology (Galah) survey aims to help scientists identify the Milky Way’s original star clusters, including the one that spawned the sun.

So far 350 stars have been profiled. Ultimately the astronomers hope to map the chemical signatures of a million stars.

Lead researcher Professor Martin Asplund, from the Australian National University (ANU), said: “This survey allows us to trace the ancestry of stars, showing how the universe went from having only hydrogen and helium – just after the Big Bang – to being filled with all the elements we have here on Earth that are necessary for life.

“Measuring each chemical element abundance to get the stellar DNA for so many stars is an enormous challenge.”

The astronomers captured light from the stars using the 3.9 metre Anglo-Australian Telescope at the ANU’s Siding Spring Observatory in New South Wales, Australia.

Splitting the light into its wavelengths, or spectra, reveals absorption patterns corresponding to different elements.

“Each chemical element leaves a unique pattern of dark bands at specific wavelengths in these spectra, like fingerprints,” said Dr Daniel Zucker, another member of the team from Macquarie University in New South Wales.

The research has been submitted for publication in the journals Monthly Notices of the Royal Astronomical Society and Astronomy & Astrophysics.

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