Astronomers have unveiled the most detailed study of the Milky Way, revealing thousands of “starquakes” and stellar DNA, and helping to identify the most habitable corners of our home galaxy.
Observations from the European Space Agency’s Gaia probe cover almost two billion stars – around 1% of the galaxy’s total number – and allow astronomers to reconstruct the structure of our home galaxy and find out how it evolved over billions of years.
Previous surveys by Gaia, a robotic spacecraft launched in 2013, have identified the movement of stars in our home galaxy in exquisite detail. By rewinding these movements, astronomers can model the transformation of our galaxy over time. The latest observations add details about chemical compositions, stellar temperatures, colors, masses and ages based on spectroscopy, where starlight is split into different wavelengths.
These measurements unexpectedly revealed thousands of starquakes, tsunami-like cataclysmic events on the surface of stars. “Starquakes tell us a lot about stars, especially about their inner workings,” said Conny Aerts of KU Leuven in Belgium, a member of the Gaia collaboration. “Gaia opens a gold mine for the asteroseismology of massive stars.”
Dr George Seabroke, Senior Research Associate at University College London’s Mullard Space Science Laboratory, said: ‘If you can see these stars changing in brightness halfway through the Milky Way, if you were anywhere near them, it would be as if the sun were changing shape. before your eyes. »
Gaia is equipped with a 1 billion pixel camera – the largest ever seen in space – with more than 100 electronic detectors. The latest dataset represents the largest chemical map of the galaxy to date, cataloging the composition of six million stars, ten times the number measured in previous terrestrial catalogs.
What stars are made of can tell us about their birthplace and subsequent journey, and help unravel the history of the Milky Way. The first primordial stars, formed shortly after the Big Bang, had only light elements – hydrogen and helium. These produced the first supernovae which enriched the galaxies with metals and elements such as carbon and oxygen, and with successive generations of stars more heavy elements became available. A star’s chemical composition is much like its DNA, giving us crucial information about its origin.
Gaia revealed that some stars in our galaxy are made of primordial matter, while others, like our Sun, are made of matter enriched by previous generations of stars. Stars closer to the center and plane of our galaxy are richer in metals than stars at greater distances. Gaia has also identified stars originally from galaxies different from ours, based on their chemical composition.
“Our galaxy is a magnificent melting pot of stars,” said Alejandra Recio-Blanco of the Côte d’Azur Observatory in France, a member of the Gaia collaboration. “This diversity is hugely important, because it tells us the story of how our galaxy formed.”
Seabroke said tracing the “gradient of metallicity” across the galaxy can help pinpoint habitable regions in the Milky Way. “If the Sun had been born in a region with much higher metallicity, there would be many more supernovae igniting, posing a risk to life on Earth,” he said.