Stars are often born in star clusters, and the solar system's sun was likely born with a group of other stars. The sun's home cluster, however, was pulled apart as it moved through the Milky Way, so the sun's star siblings are now scattered across the sky.
Finding Sun's Siblings
Astronomers expect that each of the stars in the birth cluster of the sun will share the same chemical composition, and this can help them identify the long-lost brothers and sisters of the sun.
In 2014, researchers announced that they have identified a sibling of the sun. The star called HD 162826 is more massive than the sun, but its chemical fingerprint suggests it was born in the same gas cloud where the sun was formed about 4.5 billion years ago.
DNA Of Stars
Astronomers may now be able to identify more of the sun's siblings with the help of DNA of more than 340,000 stars in the Milky Way.
Scientists involved in the Galactic Archaeology survey (GALAH), which was launched in 2013 to unravel the formation and evolution of galaxies, aim to make DNA matches between stars to find their missing siblings.
The DNA of the stars is the amount they have of each of nearly two dozen chemicals that include aluminum, iron, and oxygen.
Unlike with collecting DNA of biological beings on Earth using mouth swabs, astronomers study the starlight using a technique known as spectroscopy.
The GALAH survey used the HERMES spectrograph of the Australian Astronomical Observatory to collect the light of over 340,000 stars. These are then passed through a spectrograph that splits the light into detailed rainbows or spectra.
The astronomers would then measure the locations and the size of the dark lines in the spectra to determine the amount of each element present in a star.
Each of these chemical elements has a unique pattern of dark bands at specific wavelengths, making them comparable to fingerprints.
Implications Of Tracing The Ancestry Of Stars
Researchers said that tracing the ancestry of stars may shed light on how the universe evolved from having only helium and hydrogen just after the Big Bang to having all the elements today, including those that are crucial to life on Earth.
"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," said HERMES scientist Gayandhi De Silva, from the University of Sydney.