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The tool was launched into orbit by the European Space Agency in 2013.
The European Space Telescope Gaia will reveal the first part (EDR3) of a catalog of over 1,800 million celestial objects in our galaxy this Thursday, December 3, observed with unparalleled precision.
This event is highly anticipated by thousands of scientists around the world. The telescope was launched into orbit by the European Space Agency in 2013.
Gaia is stationed 1.5 million kilometers from Earth, in the opposite direction to the Sun, to better protect herself from its radiation. Protected by a sort of shield to avoid the impacts of micrometeorites, its two optics sweep through space slowly, with a complete revolution in six hours.
The telescope detects and observes a very small part of the stars in our galaxy, which are 100,000 light-years in diameter and beyond. Its catalog lists a plethora of celestial objects, ranging from all known varieties of stars, exoplanets and asteroids, to the interstellar medium and galactic clouds near our Milky Way.
These observations, detected by a set of almost one gigapixel photocells, allow to locate their position, distance and displacement. By measuring their physical characteristics, scientists can better understand the formation and evolution of stars and our galaxy.
After a first catalog in 2016, it is thanks to the second, delivered in 2018, with 1,700 million sources, that scientists have determined, for example, that our Milky Way has “merged” with another galaxy ten billion years does. A third catalog will be presented on Thursday.
A revolution in knowledge
Gaia caused “a revolution in knowledge,” Catherine Turon, astronomer emeritus of the Paris-PSL Observatory, a pioneer in space astrometry and involved in the mission from the beginning, told AFP.
One of these intergalactic collisions “corresponds to the age of our solar system, which leads to the hypothesis that with each collision there is a burst of star formation”, of which our sun would be a part.
“The discoveries will multiply,” says Chantal Panem, head of mission of the National Center for Space Studies (CNES), noting that “some 3,800 scientific articles have been published using Gaia data” from the second catalog.
The third enriches the previous ones, with 1,800 million celestial objects, and “above all much better astrometric and photometric accuracies”, according to Catherine Turon.
The measurement of the displacement of the stars is two to three times more accurate and the calculation of their distance has been improved by 30% compared to the previous catalog. This progress is largely due to the accumulation of data studied during 34 months of observation, compared to 22 months for the second catalog.
Until the 1990s it was possible to determine the position of just 8,000 stars from Earth by measuring angles, the parallax method.
Gaia’s precursor Hipparcos has revolutionized the field since its launch by the European Space Agency in 1997, cataloging more than 110,000 celestial objects. Gaia has a thousand times greater measurement accuracy.
Colossal volumes of data
The disadvantage of this extreme accuracy is that the volumes of data to “digest” and process are getting bigger and bigger. To date, Gaia has transmitted more than 80,000 trillion bytes. A volume that mobilizes a large IT platform of the CNES in France and those of the European partners.
And this explains why it took more than three years to produce and validate this first part of the catalog, “which includes the positions, distances, motion and magnitudes of the stars,” explained Catherine Turon.
The second part, with, for example, data on the physical characteristics of observed objects, the classification of variable stars and data on the Andromeda galaxy, will be available in the first half of 2022.
The end of the Gaia mission is now scheduled for 2025. “We won’t have a final catalog until 2028, at best,” says Chantal Panem.
From here until then, we can expect great discoveries, according to Catherine Turon, such as “for example, a complete census of all massive exoplanets around the solar quarter”.
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