Gaia: major discoveries are coming, some of which will challenge our knowledge

If all of us interested in space science wait for the first images from the James-Webb space observatory — which will be made public on July 12 — the community of astronomers is excited and amazed today for the release of the mission’s third data catalog Gaia. Unlike other missions, which target specific objects, Gaia is a “simple” survey mission. So don’t expect to see pretty pictures of the Universe.

If astronomers around the world are eagerly awaiting this data, it is because Gaia’s performance is unprecedented. Indeed, this satellite is capable of observing all objects up to 400,000 times fainter than the faintest of stars observable ateye naked. As a result, this catalog, which contains new and improved details for nearly two billion stars in our galaxy, is the reference in astronomy. It lists some 1.8 billion celestial objects with unprecedented astrometric and photometric precision and represents a major advance over the previous catalog (DR2) in terms of the precision, accuracy and homogeneity of astrometric and photometric data. .

Huge potential for information

To understand why “simple” measurements excite astronomers and astrophysicistsit should be known that, for each star that it can detect in the galaxy, Gaia is able to measure its position and its movement each time in three dimensions, its color as well as its properties physical and even chemicals for the shiniest. It is not a new, slightly improved description of the galaxy, but a more than significant enrichment of knowledge.

Gaia’s data will be useful to all areas of astronomy and science.astrophysics. There is not a single astronomer, whether historianchemist or physicist, which will not use its data, directly or indirectly. We therefore expect new discoveries, a significant progress in our understanding of the Universe and, more surprisingly, a questioning of a certain amount of knowledge.

There is not a single astronomer, whether historian, chemist or physicist, who will not use his data, directly or indirectly

New to this dataset is the largest catalog of stars to date binariesthousands of Solar System objects such as asteroids and satellites of planets as well as, beyond the Milky Waymillions of galaxies and quasars.

Launched in December 2013 to map in 3D more than a billion objects in our galaxy with unparalleled precision, Gaia should operate until 2025. Five years were needed to deliver this third catalog of observations spread from 2014 to 2017 It will therefore be necessary to wait until 2030 to obtain the final version of the Gaia catalog.

Surprising discoveries

Several findings were presented today. Thus, we learn that some stars in our galaxy are made up of matter paramount while others, like our Sun, are made of material enriched by previous generations of stars. Stars closer to the center and plane of our galaxy are richer in metals than stars at greater distances.

Gaia has also identified stars originally from galaxies different from ours, based on their chemical composition. This diversity is extremely important, because it tells us the story of the formation of our galaxy. It reveals the processes of migration within our galaxy and of accretion from outer galaxies. It also clearly shows that our Sun and we all belong to an ever-changing system, formed by the assembly of stars and gas of different origins says Alejandra Recio-Blanco of the Côte d’Azur Observatory in France, a member of the Gaia collaboration.

More surprisingly, Gaia was able to detect stellar quakes which appear as tiny movements on the surface of a star, which change the shape of stars says Conny Aerts from KU Leuven in Belgium, a member of the Gaia collaboration. Finally, a new catalog of binary stars presents the characteristics orbitals of more than 800,000 of these binary systems, while a new study of 156,000 asteroids delves deeper into the origin of our solar system. Gaia also reveals information about 10 millionvariable starsmysterious macromolecules between stars as well as quasars and galaxies beyond our own cosmic neighborhood.

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