Gaia satellite reveals the most accurate map of the Milky Way ever drawn

The telescope, located 1.5 million kilometers from Earth to the Sun, scanned 1% of our galaxy and was able to provide information about more than 1.8 billion stars.

This is an unprecedented collection that offers scientists a true mine of information. The Gaia Space Telescope delivered its new data of nearly two billion stars in the Milky Way on Monday with unprecedented precision, making it possible to draw a multidimensional map of our galaxy, bubbling with life, with unmatched precision.

“It’s a fantastic day for astronomy, which opens the floodgates for new discoveries about the universe and our galaxy,” said Josef Aschbacher, Director General of the European Space Agency (ESA), during the presentation of the results of Gaïa, one of the Agency’s scientific flagships. missions launched in 2013.

1% of the galaxy was scanned, but already analyzed 1.8 billion stars

“Before Gaïa, we had a medieval vision of the world that lacked continents, poorly known country profiles. Since 2016, we have had a very precise vision of the continents that we have on Earth. And this Monday, galactic landscapes are revealed, with new information about the species of objects or dust between the stars, “explains Alejandra Recio-Blanco, of the Côte d’Azur Observatory.

The space observatory, located 1.5 million kilometers from Earth to the Sun, is in its third data harvest, intended to map our galaxy in all its dimensions and thus understand its origin, its structure and its dynamics.

In this image released by the European Space Agency (ESA) on June 13, 2022, an artistic impression of the Milky Way and above a overlay showing the location and density of a sample of young stars from version 3 of the Gaia data (in yellow -green).  The sign
In this image released by the European Space Agency (ESA) on June 13, 2022, an artistic impression of the Milky Way and above a overlay showing the location and density of a sample of young stars from version 3 of the Gaia data (in yellow -green). The sign “you are here” points to the Sun. © EUROPEAN SPACE AGENCY / AFP

Equipped with two telescopes and a one billion pixel photographic sensor, Gaia scans only a very small proportion (almost 1%) of the stars in our galaxy, whose diameter measures 100,000 light-years. However, it analyzed 700 million data every day for 34 months and was able to provide information on more than 1.8 billion stars.

Unsurpassed precision

A host of unprecedented details are provided, such as these 220 million photometric spectra, which will allow for the first time to estimate the mass, color, temperature and age of stars.

And 2.5 million new chemical compounds, this “DNA” informs about the birthplace of the stars and their journey through the galaxy. Or 35 million radial velocities, which measure the displacement of the stars and provide a new understanding of the movements of the Milky Way.

“Turbulent” and not “patachonne”

Surprise for scientists: Gaia first discovered the star “quake”, small movements on the surface of a star that changed its shape. The discovery opens “a goldmine for ‘asteroseismology’ of massive stars”, namely their inner function, explained Conny Aerts from the University of Louvain (Belgium), a member of the Gaia Collaboration.

“At all levels, Gaia exceeds expectations,” welcomes François Mignard, Scientific Head of the Gaia Mission for France.

These results thus paint the portrait of a galaxy “much more turbulent” than expected. “We thought it had reached a stationary state, turning it gently around itself, like a liquid gently stirred with a wooden spoon. But not at all!”, François Mignard develops.

Her “‘patachon’s life’ consists on the contrary of accidents, unexpected movements and not as simple” as this spiral she describes. For example, our solar system is “not content to rotate in a perpendicular plane, it goes up and down, above and below,” specifies François Mignard.

The final version is scheduled for 2030

It is also home to a very heterogeneous population of stars, some of which were not there from the start, but which may have been “swallowed up” along the way through interactions with the nearby Sagittarius’ dwarf galaxy.

“Our galaxy is a magnificent melting pot of stars,” sums up Alejandra Recio-Blanco. Gaia’s level of precision is such that it “will allow us to trace the Milky Way’s past over more than 10 billion years,” added Anthony Brown, president of the international consortium DPAC, the soil treatment chain for the data stream sent by Gaia.

Stars have the special thing about living for billions of years: analyzing them is like studying a fossil, informing us about the state of the galaxy during its formation, astronomers emphasize. With the second catalog, delivered in 2018, astronomers were able to show that our galaxy was “fused” another ten billion years ago.

The new catalog also offers unmatched precision measurements for 156,000 asteroids in our solar system, breaking down the composition of 60,000 of them. It will have taken five years to deliver this third catalog of observations spread from 2014 to 2017. And it will be necessary to wait until 2030 to get the final version, when Gaia finishes scanning the space, in 2025.

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