Stars are divided into three broad categories related to their chemical compositions. Astronomers from the University of Cambridge think they can go a step further and use the elements found in stars to link how they are related to one another, like a "family tree".
In a paper published in the Monthly Notices of the Royal Astronomical Society, the researchers picked 22 stars, including our own Sun, and using 17 chemical elements as a proxy for the “stellar DNA” were able to identify three branches of related stars.
The researchers took a leaf out of biology books, which use a system called phylogenetic trees to study how living organisms are related to each other. The team thought that they could create a similar approach to see how stars have evolved in the Milky Way.
“The differences between stars and animals is immense, but they share the property of changing over time, and so both can be analyzed by building trees of their history,” co-author Professor Robert Foley, of the Leverhulme Centre for Human Evolutionary Studies at Cambridge, said in a statement.
Obviously, stars don’t have DNA so the researchers had to be a bit creative, instead using the abundance of different chemical elements. The first generation of stars was made almost exclusively of hydrogen and over time they have produced the other elements. The stars then died explosives death and disseminated those elements across the universe.
Later generations of stars have formed from hydrogen clouds polluted with those elements and contributed in different ways to future enrichment. By combining the position of the stars on the tree with their age, the team was able to estimate the chemical enrichment age and also the distribution of elements in the solar neighborhood.
The family trees of stars, including the Sun, composed by the researchers. Institute of Astronomy
“The use of algorithms to identify families of stars is a science that is constantly under development,” lead author Dr Paula Jofré added. “Phylogenetic trees add an extra dimension to our endeavors, which is why this approach is so special. The branches of the tree serve to inform us about the stars’ shared history.”
The team hopes to find a place for every star in the Milky Way on the phylogenetic tree. Detailed composition of stars is required for such a thing, but surveys like GAIA and future observatories could go a long way in connecting stars through both space and time.