It is an unprecedented collection of incredible precision that shows the Milky Way in a new light. The Gaia Space Telescope delivered its third dataset on Monday, June 13, to provide more details about the Milky Way’s approximately two billion stars and to draw the multidimensional map of our galaxy with unmatched precision.
Launched in 2013, the European space telescope Gaia maps our galaxy in three dimensions. Stationed 1.5 million kilometers from our planet, opposite the Sun, it filters through a small part of the stars in our galaxy using two telescopes and a billion-pixel photographic sensor. . His goal? Stars with a diameter of 100,000 light-years.
The Space Observatory is now in its third harvest of data. The figures, released on Monday, have shocked scientists. By searching the 700 million pieces of data sent to Earth daily for almost three years, more than 1.8 billion stars have been mapped from all angles. Scientists were also able to gather information such as the distance that separates them from the Earth, their speed of movement or their chemical composition, which is crucial for understanding their origin, their structure and their dynamics.
A galaxy more turbulent than expected
Among the many advances in its study, the telescope in particular has made it possible to establish 220 million photometric spectra, which will help scientists estimate for the first time the mass, temperature, color and age of stars, as well as 2.5 million new chemical compositions containing the birthplace of the stars and their journey through the galaxy. Gaia also discovered for the first time star tremors, small movements on the surface of stars that change their shape.
“It is an amazing 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. “On all levels, Gaia exceeds expectations“, Welcomed with AFP François Mignard, Scientific Director of the Gaia Mission for France.
The results, which gave rise to about fifty scientific articles in the process, paint the portrait of a galaxy “much more turbulent” than expected, told AFP, the astronomer from the Observatory of the Coast. Azure. “We thought it had reached a stationary state, turning it gently on 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.
Tracing of the Milky Way’s past over 10 billion years
It is also home to a very heterogeneous population of stars, some of which were not there from the beginning, 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 of the Côte d’Azur Observatory.
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 together” 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.