The branches of the tree serve to inform us about the stars' shared history.
- Dr Paula Jofré
By studying chemical signatures found in the stars, they are piecing together these evolutionary trees looking at how the stars formed and how they are connected to each other. The signatures act as a proxy for DNA sequences. It’s akin to chemical tagging of stars and forms the basis of a discipline astronomers refer to as Galactic archaeology.
It was Charles Darwin who in 1859 published his revolutionary theory that all life forms are descended from one common ancestor. This theory has informed evolutionary biology ever since but it was a chance encounter between an astronomer and a biologist over dinner at King’s College in Cambridge that got the astronomer thinking about how it could be applied to stars in the Milky Way.
Writing in Monthly Notices of the Royal Astronomical Society, Dr Paula Jofré, of the University of Cambridge’s Institute of Astronomy, describes how she set about creating a phylogenetic “tree of life” that connects a number of stars in the galaxy.
“The use of algorithms to identify families of stars is a science that is constantly under development. Phylogenetic trees add an extra dimension to our endeavours which is why this approach is so special. The branches of the tree serve to inform us about the stars’ shared history,“ she says.
The team picked 22 stars, including the Sun, to study. The chemical elements have been carefully measured from data coming from ground-based high-resolution spectra taken with large telescopes located in the north of Chile. Once the families were identified using the chemical DNA, their evolution was studied with the help of their ages and kinematical properties obtained from the space mission Hipparcos, the precursor of Gaia, the spacecraft orbiting Earth that was launched by the European Space Agency and is almost halfway through a five-year project to map the sky.
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Image: a family of trees in our solar system, including the Sun
Credit: Institute of Astronomy
Reproduced courtesy of the University of Cambridge
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