Astronomers have mapped the ‘DNA’ of 350,000 stars in our Galaxy as part of a mission to find the lost siblings of our Sun. The mission, called the Galactic Archaeology survey (GALAH), was launched in 2013 and its goal is to learn more about the formation and evolution of the Milky Way.
When complete, it is expected to reveal the original star clusters of the Milky Way, including the one in which the Sun was born.
That cluster was pulled apart by the Milky Way and flung across the Galaxy, but every star born in that cluster will have the same chemical composition.
“This survey allows us to trace the ancestry of stars, showing astronomers 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,” says Professor Asplund of the Australian National University, which is involved in the research.
For each star in the survey, the team will calculate how much they contain of nearly two dozen chemical elements like oxygen, aluminium and iron.
They do this by splitting the light from each star into its individual components using a technique called spectroscopy.
“Each chemical element leaves a unique pattern of dark bands at specific wavelengths in these spectra, like fingerprints,” says Associate Professor Daniel Zucker of the Australian Astronomical Observatory.
It takes about an hour to collect enough photons of light for each star, although the team can observe 360 stars at the same time using fibre optics.
To date, the GALAH team has spent 280 nights at the telescope since 2014, collecting data for the mission.