Astronomers have unveiled the most detailed survey of the Milky Way, revealing thousands of “earthquakes” and stellar DNA, and helping to identify the most habitable corners of our home galaxy.
Observations from the European Space Agency’s Gaia spacecraft cover nearly two billion stars, about 1% of the total number of the galaxy, and allow astronomers to reconstruct the structure of our galaxy and discover how it has evolved over billions of years.
Previous surveys of Gaia, a robotic spacecraft launched in 2013, have pointed to the movement of stars in our home galaxy in exquisite detail. By rewinding these movements, astronomers can model how our galaxy has transformed over time. The latest observations add details of chemical compositions, stellar temperatures, colors, masses, and ages based on spectroscopy, where starlight is divided into different wavelengths.
These measurements unexpectedly revealed thousands of earthquakes, tsunami-like cataclysmic events on the surface of the stars. “The Starquakes teach us a lot about stars, in particular how they work internally,” said Conny Aerts of KU Leuven in Belgium, who is a member of the Gaia collaboration. “Gaia is opening a gold mine for massive star asterosismology.”
Dr George Seabroke, a senior research associate at Mullard Space Science Laboratory at University College London, said: as if the sun were changing in front of your eyes. “
Gaia is equipped with a 1 billion pixel camera, the largest ever in space, with more than 100 electronic detectors. The latest data set represents the largest chemical map in the galaxy to date, cataloging the composition of six million stars, ten times the number measured in previous terrestrial catalogs.
What the stars are made of can tell us their place of birth and their subsequent journey, and help unravel the history of the Milky Way. The first major stars, formed shortly after the Big Bang, had only light elements – hydrogen and helium – available. These produced the first supernovae to enrich galaxies with metals and elements such as carbon and oxygen, and with successive generations of stars, heavier elements became available. The chemical composition of a star is somewhat similar to its DNA, which gives us crucial information about its origin.
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Gaia revealed that some stars in our galaxy are made of primordial material, while others like our Sun are made of matter enriched by previous generations of stars. Stars that are closer to the center and plane of our galaxy are richer in metals than stars at greater distances. Gaia also identified stars that originally came from galaxies other than our own, based on their chemical composition.
“Our galaxy is a beautiful crucible of stars,” said Alejandra Recio-Blanco of the Côte d’Azur Observatory in France, who is a member of the Gaia collaboration. “This diversity is extremely important, because it tells us the history of the formation of our galaxy.”
Seabroke said tracking the “metallic gradient” across the galaxy could help identify the habitable regions of the Milky Way. “If the Sun were born in a region with much higher metallicity, there would be many more supernovae that would go out, posing a risk to life on Earth,” he said.
The title of this article was modified on June 13, 2022. The original version referred to the “stella” DNA. The correct spelling is “stellar”.