Earthquake-like movements spotted on the surface of thousands of stars are some of the most intriguing new findings by the European Space Agency’s (ESA) Gaia space observatory.


Since its launch in 2013, the spacecraft has been on a mission to create the most accurate map of the Milky Way ever. Now, with its third data release, Gaia has published a raft of new findings including observations of unusual oscillations, known as starquakes, that ripple along the surface of stars – something it was never originally designed to detect.

“Starquakes teach us a lot about stars, notably their internal workings. Gaia is opening a goldmine for ‘asteroseismology' of massive stars,” said Gaia scientist Prof Conny Aerts of KU Leuven in Belgium.

The spacecraft’s latest release contains data on almost two billion stars, including detailed information about temperature, age, movements and chemical composition.

Astronomers can learn a wealth of information about stars by studying their chemical composition. Shortly after the Big Bang, the Universe consisted mainly of light elements, such as hydrogen and helium. The heavier elements, such as carbon and nitrogen, were created in the centre of stars, forming as the lighter elements collapsed under the influence of gravity.

When stars die, they release these heavier elements out into the Universe, which then go on to form new stars. This means that the chemical composition of stars can tell astronomers about their origin and lifecycles.

Astronomers can determine the composition of a star by using spectroscopy – a technique that analyses the light from a star to determine what chemicals are present inside it.

Data from Gaia shows that some stars in the Milky Way are made from primordial material while others, such as the Sun, are composed of material made in previous generations of stars.

“Our galaxy is a beautiful melting pot of stars,” said Gaia scientist Alejandra Recio-Blanco of the Observatoire de la Côte d’Azur in France.

“This diversity is extremely important, because it tells us the story of our galaxy’s formation. It reveals the processes of migration within our galaxy and accretion from external galaxies. It also clearly shows that our Sun, and we, all belong to an ever-changing system, formed thanks to the assembly of stars and gas of different origins.”

The Gaia scientists have also used the new data to compile a catalogue of more than 800,000 binary star systems, 156,000 asteroids and a host of quasars and other cosmic bodies that lay outside of our solar system.

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“Unlike other missions that target specific objects, Gaia is a survey mission. 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,” said Gaia scientist Timo Prusti.
“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.”

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Jason Goodyer
Jason GoodyerCommissioning editor, BBC Science Focus

Jason is the commissioning editor for BBC Science Focus. He holds an MSc in physics and was named Section Editor of the Year by the British Society of Magazine Editors in 2019. He has been reporting on science and technology for more than a decade. During this time, he's walked the tunnels of the Large Hadron Collider, watched Stephen Hawking deliver his Reith Lecture on Black Holes and reported on everything from simulation universes to dancing cockatoos. He looks after the magazine’s and website’s news sections and makes regular appearances on the Instant Genius Podcast.