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The red dwarf doesn’t fall far from the tree. Astronomers are borrowing a technique from biology to build a family tree of the origins of stars.

A star’s chemical make-up can tell you a lot about where it came from. The universe’s first stars were mostly made of hydrogen and helium, and they fused those elements together into heavier ones. When massive stars explode as supernovae, they disperse the heavier elements they’ve built into space, where they become the building blocks of the next generation of stars. Stars born after many generations have heavier elements in greater abundance than do older ones.

“This process of ‘descent’ mirrors that of biological descent, even though biological evolution is driven by adaptation and survival, while chemical evolution is driven by mechanisms that lead to the death and birth of stars,” write at the University of Cambridge and her colleagues.

Stellar DNA

Stars move around the galaxy’s spiral arms and disc, making it difficult to figure out where they came from. But if they were born in the same cluster, stars should have similar chemical signatures.

Astronomers use chemical tagging to try to identify stellar siblings even if they have drifted apart. But Jofré and her colleagues thought they could take this a step further by taking a page from evolutionary biology.

“This is an invitation for astronomers to think in a new way about the history of stars and interpret their past,” Jofré says. “A lot more information could be extracted.”

Combining traces of 17 chemical elements as stellar “DNA”, the team categorised 22 stars in our galactic neighbourhood.

Galactic tree

Using this approach, the team assembled a tree with three branches associated with stars of different origins. They tentatively argue that the thicker part of the galaxy’s disk forms new stars more rapidly than elsewhere in the Milky Way, which is consistent with other research. They also found that some stars may have even originated from another galaxy that collided with the Milky Way long ago.

at the University of Sydney in Australia likens this to DNA sequencing of humans, which can help trace people’s origins.

“This is a proof of concept,” says Martin Asplund, an astrophysicist at the Australian National University in Canberra.  “The tree they find is reasonable, but you need careful stellar measurements for many, many more stars.”

Those measurements should come from the European Space Agency’s Gaia spacecraft and the US APOGEE survey, as well as GALAH in Australia, which will provide information about hundreds of thousands of stars around the Milky Way.

Journal reference: Monthly Notices of the Royal Astronomical Society,