The GALAH (GALactic Archaeology with HERMES) survey has released its fourth data set, providing vital information on over 1 million stars in our Milky Way galaxy. This groundbreaking project, led by an international team of scientists, offers unprecedented insights into the formation, evolution, and chemical composition of our cosmic home. The data will help astronomers unravel the mysteries of stellar nucleosynthesis and the early universe, paving the way for exciting new discoveries.

Mapping the Chemical Fingerprints of Stars

The GALAH survey has been harvesting data for more than a decade now, using the 4-metre Anglo-Australian Telescope (AAT) and its High Efficiency and Resolution Multi-Element Spectrograph (HERMES) instrument. The DR4, now available for download, showcases the spectra — the chemical fingerprints — of nearly 1 million stars in our Milky Way.

This spectra tell researchers which elements are present within the stars and therefore have allowed us to track where the various chemical building blocks of life came from – back to their very birthplaces. Scientists use these absorption lines in the stellar spectra to infer the presence and amount of elements—carbon, nitrogen, oxygen—as well as heavy metals like those in our smartphones and electric cars. This is priceless information, as this could lead to unraveling the mysteries of stellar nucleosynthesis and offer a detailed insight into how our galaxy was formed and evolved.

Mapping the Chemistry and Kinematics extraction sketch of the entire Milky Way.

That is, the GALAH data release has been a breakthrough in our attempt to understand the Milky Way galaxy. Together with the chemical information in the stellar spectra and data from other missions (such as Gaia, Kepler, CoRoT), we can now measure precise ages for these stars. They can then map its chemical and dynamical evolution in detail: not only the way the star-formation history changes with redshift, but also how many of these events happened at what time designed to give them as complete a timeline as possible back along the redshedt axis.

Dr. Sven Buder, the project’s lead researcher said: “With this data, astronomers get a powerful tool to test out new theories and explore previously uncharted territory of the universe.” This allows scientists to trace the elements forming and being distributed creating a window into cosmic evolution and the birthplaces of atoms that make up life. The data might better yet tell us about the Milky Way’s history, for instance when stars gluttonously consumed their satellite planets in the galaxy’s growth.

Powering the future of astronomy

Not only is the GALAH dataset a goldmine of information for existing research — but it also holds great promise for breakthroughs yet to be made. These are likely to be crucial in training the next wave of machine-learning tools that will ever so gradually come to dominate astronomy.

According to University of New South Wales Associate Professor Sarah Martell, “We are actually heading into a remarkably rich time over the next decade… where all of these discoveries about what’s happening with our universe are going to be made based upon the data that we’ve collected right here in Australia using Australian telescopes and building on Australian research.” The legacy of the GALAH project will continue for many decades, through its comprehensive and irreplaceable reference today for astronomers across the globe to make sense of the night sky.