Gaia has seen two billion stars

It’s a big surprise: the European Gaia satellite has seen tremors on the surfaces of thousands of stars, even those that are theoretically impossible. The find was particularly striking, because Gaia was not built to detect these types of quakes.

The news came out Monday when the European Space Agency (ESA) shared a new database of data collected by the satellite with the world. Launched in 2013, Gaia creates an accurate map of the Milky Way, the egg-shaped galaxy about 100,000 light-years across that houses Earth. This map data helps astronomers understand the evolution of the Milky Way.

Gaia’s first star map was published in 2016. It was not yet accurate and contained only about two million stars. The database was updated in 2018. At that time, it consisted of data about the movements of 1.3 billion stars. In 2020, ESA already shared a subset of the third dataset, which was published in full this Monday, which is almost two billion stars in size.


Gaia orbits the sun, one and a half million kilometers further than the Earth orbits the sun. This is also the zone where the new James Webb space telescope is located. The two telescopes aboard Gaia can see anything in the sky that’s bright enough to detect: stars, as well as moons, asteroids and dust.

Gaia’s database has already yielded many discoveries. On average, astronomers around the world publish about five scientific articles a day based on this database. The database, published Monday, 10 terabytes in size, doesn’t just contain information about more stars, more data about those stars is also available. “The database has been supplemented with the DNA of the stars, such as the chemical composition and temperature,” says Amina Helmi of the University of Groningen. She was involved with Gaia ‘s data team and just ate a cake with a photo taken by Gaia on it .

Anthony Brown, from Leiden University and head of the data team, is happy. “I expect this update to have an even greater impact on astronomy than the previous one. The now released dataset is the richest astronomical dataset ever published. It contains all the fundamental properties of stars.”

So one of the most striking new discoveries is that Gaia can now also see starquakes, even though the satellite was not built for this. Starquakes occur when energy generated within a star moves outward, causing the star to vibrate. Brown: “We can already see that these starquakes also occur in stars where we do not expect them based on their properties.”

Investigating starquakes is just one example of what astronomers will do with the new database. Helmi will use the data in her research into the origin of the Milky Way. “In 2018, we were able to study which direction stars came from based on movements. For example, we discovered that many of the ancient stars came from outside the Milky Way. Now we have information about the properties of stars. That reveals how and under what conditions those stars were born.”

Vincent Icke of Leiden University and not involved in the Gaia Team, says about the new database: “It is as if you can make out on a photo of a church in which order and in which year the individual stones were placed and where all those stones were placed. are made of and come from, of baked clay from the Maas or from the Waal. Fantastic”

It is expected that Gaia will stop observing in 2025: by then the fuel will run out.

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