The event is awaited by thousands of scientists around the globe (it will be live here). The European Gaia space telescope unveils, Thursday, December 3, the first part (EDR3) of a catalog of more than 1.8 billion celestial objects in our galaxy, observed with unparalleled precision.
Put into orbit by the European Space Agency (ESA) in 2013, Gaia is stationed 1.5 million kilometers from Earth, opposite the direction of the sun, to better protect itself from its radiation. Sheltered under a hood that shields the impacts of micrometeorites, its two optics sweep the space slowly, with a complete turn in six hours.
The telescope, which is the most advanced ever in Europe, detects and observes a very small part of the stars in our galaxy. Its catalog lists a host of celestial objects, ranging from all known varieties of stars, exoplanets and asteroids, to the interstellar medium and galactic clouds close to our Milky Way.
These observations, detected by an assembly of photo cells of almost a gigapixel, make it possible to locate their position, distance and displacement. With the measurements of their physical characteristics, scientists can better understand the phenomena of formation and evolution of stars, and of our galaxy.
After a first catalog in 2016, it is thanks to the second, delivered in 2018 with 1.7 billion sources, that scientists have determined for example that our Milky Way had “merged” with another galaxy, ten billion years ago. It is therefore a third catalog which is unveiled Thursday.
Gaia trained “a knowledge revolution”, told AFP Catherine Turon, astronomer emeritus at the Paris-PSL Observatory, a pioneer of space astrometry and involved in the mission from its inception. One of those intergalactic collisions “corresponds to the age of our solar system, leading to the hypothesis that with each collision there is an outbreak of star formation”, of which our sun would be part.
“The discoveries will multiply”, affirms for her part Chantal Panem, head of mission at the National Center for Space Studies (CNES), noting that “around 3,800 scientific papers using Gaia data have been published “, from the second catalog. The third enriches the previous ones, with 1.8 billion celestial objects, and “especially much better astrometric and photometric precision”, according to Catherine Turon.
The measurement of the displacement of stars is two to three times more precise, and the calculation of their distance has been improved by about 30% compared to the previous catalog. Progress due in large part to the accumulation of data studied, over 34 months of observation, against 22 for the second catalog. The end of Gaia’s mission is now scheduled for 2025. “We won’t have a final catalog before 2028, at best”, thinks Chantal Panem. Until then, we can expect major discoveries, according to Catherine Turon, with “for example the exhaustive census of all massive exoplanets all around the solar neighborhood”.
