Astronomers have unveiled the most detailed survey of the Milky Way, revealing thousands of “stellar earthquakes” and stellar DNA, and helping to identify the most habitable corners of our galaxy.
Observations from the European Space Agency’s Gaia probe cover nearly two billion stars – about 1% of the total number in the galaxy – and allow astronomers to reconstruct the structure of our galaxy and see how it evolved over billions of years.
Previous surveys by Gaia, a robotic spacecraft launched in 2013, has precisely mapped the motion of stars in our home galaxy in great detail. By rewinding these motions, astronomers can model how our galaxy has transformed over time. Recent observations add details of chemical compositions, stellar temperatures, colours, masses and ages based on spectroscopy, where starlight is split into different wavelengths.
These measurements unexpectedly revealed thousands of stellar earthquakes, tsunami-like catastrophic events on the surface of stars. “The Starquakes learned a lot about stars – in particular, their inner workings,” said Connie Aerts of KU Leuven in Belgium, who is a member of the Gaia cooperative. “Gaya opens a stellar flower gold mine for massive stars.”
Dr George Seabrook, senior research associate at the Mullard Space Science Laboratory at University College London, said: “If you could see these stars shifting halfway through the Milky Way, if you were anywhere near them, it would be like changing the shape of the Sun. before your eyes.”
Gaia is equipped with a 1bn pixel camera – the largest ever in space – and complete with more than 100 electronic detectors. The latest dataset represents the largest chemical map of the galaxy to date, classifying the formation of six million stars, ten times the number measured in previous terrestrial catalogs.
The material that stars are made of can tell us where they were born and next, and help reveal the history of the Milky Way. The first primordial stars, which formed shortly after the Big Bang, had only the lightest elements – hydrogen and helium – available. These produced the first supernovae that enriched galaxies with metals and elements such as carbon and oxygen, and with successive generations of stars more and more heavy elements became available. The chemical composition of the star is somewhat similar to its DNA, which gives us important information about its origin.
Gaia revealed that some stars in our galaxy are made of primitive materials, while others, like our sun, are made of material enriched by previous generations of stars. The stars closest to the center and plane of our galaxy are richer in minerals than stars at greater distances. Gaia also identified stars that originally came from galaxies different from our own, based on their chemical makeup.
“Our galaxy is a beautiful melting pot of stars,” said Alejandra Recio Blanco of the Observatoire de la Côte d’Azur in France, a member of the Gaia collaboration. “This diversity is very important, because it tells the story of the formation of our galaxy.”
Tracking a “metallic gradient” across the galaxy could help identify habitable regions in the Milky Way, Seabrook said. “If the Sun was born in a region with a much higher mineral content, there would be more supernovae exploding, which would be a danger to life on Earth,” he said.
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