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Strange and unexpected tsunami-like starquakes — movements on stars’ crusts similar to earthquakes we experience on our planet — have been revealed by the European Space Agency’s Gaia space observatory.
The unusual starquakes are among multiple new discoveries made by Gaia, a mission launched in 2013 to create the “most accurate and complete multi-dimensional map of the Milky Way.” On Monday, ESA released its third batch of data from the spacecraft, revealing fresh details on nearly 2 billion stars in our galaxy.
“Starquakes teach us a lot about stars, notably their internal workings. Gaia is opening a goldmine for ‘asteroseismology’ of massive stars,” said Conny Aerts, a professor at the Institute of Astronomy at KU Leuven in Belgium and a member of the Gaia collaboration, a group of 400 researchers that work on the data from the project, in an ESA news release.
The agency described the stellar vibrations spotted by Gaia as “large-scale tsunamis” that changed the shape of stars. Gaia wasn’t originally designed to detect the phenomenon but was able to discern strong movement on the surface of thousands of stars, including some where starquakes had seldom been seen before.
Previously, Gaia had detected radial oscillations — motions diverging from a common point — that caused some stars to swell and shrink periodically while keeping their spherical shape. The newly discovered oscillations were non-radial.
Gaia is uniquely positioned about 930,000 miles from Earth in the opposite direction from the sun. The spacecraft carries two telescopes that can scan our galaxy from a location called the Lagrange 2, or L2, point. At this point, the spacecraft is able to remain in a stable spot due to the balance of gravitational forces between Earth and the sun.
This also means that the spacecraft doesn’t have any interference from Earth’s light, and it can use the minimum amount of fuel to remain in a fixed position. The vantage point allows Gaia to have unfettered views and continuously scan our galaxy.
“With this incredible database we can build a comprehensive picture of the Milky Way and delve into its incredible history of formation, seeing direct evidence of both violent past interactions with other galaxies, and internal bouts of intense star formation along (the Milky Way’s) spiral arms,” said Nicholas Walton, a research fellow at Institute of Astronomy at University of Cambridge and member of the ESA Gaia collaboration, in a statement.
Much of the latest information about the Milky Way was revealed by Gaia’s newly released spectroscopy data, resulting from a technique in which the starlight is split into its constituent colors, like a rainbow.
The data gathered by Gaia includes new information on the chemical composition, temperatures, mass, and age of stars, as well as the speed at which they move toward or away from Earth. Detailed information about more than 150,000 asteroids in our solar system and space dust — what lies between stars — was also released.
Data from Gaia reveals the speed at which more than 30 million Milky Way stars move toward or away from Earth. Blue shows the parts of the sky where the average motion of stars is toward us and red shows the regions where the average motion is away from us.
“Gaia’s chemical mapping is analogous to sequencing the DNA of the human genome,” said George Seabroke, a senior research associate for the Mullard Space Science Laboratory at University College London, in a statement from the Royal Astronomical Society.
“The more stars we know the chemistry for, the better we can understand our galaxy as a whole. Gaia’s chemical catalogue of six million stars is ten times larger than previous ground-based catalogues, so this is really revolutionary. Gaia’s data releases are telling us where stars were located and how they are moving. Now we also know what a lot of these stars are made of,” Seabroke said.
About 50 scientific papers based on the Gaia data will be published on Monday; some will appear in a special issue of the journal Astronomy & Astrophysics.
“Unlike other missions that target specific objects, Gaia is a survey mission,” said Timo Prusti, project scientist for Gaia at ESA.
“This means that while surveying the entire sky with billions of stars multiple times, Gaia is bound to make discoveries that other more dedicated missions would miss,” Prusti said. “This is one of its strengths, and we can’t wait for the astronomy community to dive into our new data to find out even more about our galaxy and its surroundings than we could’ve imagined.”
