France Press Agency, Published on Saturday, June 11, 2022 at 10:30 p.m.
The Gaia mission, whose space telescope maps the Milky Way in detail, unveiled on Monday a new informative version of the nearly two billion stars that have charted their path and analyzed properties.
“It is the Swiss Army knife of astrophysics. There is not a single astronomer who does not use his data directly or indirectly,” the Ivorian astronomer told AFP. France.
The community of astronomers will be able to draw from Monday, from 10:00 GMT, the third catalog of data collected by the instrument. Harvest, accompanied by about fifty academic papers, lists a number of celestial bodies.
From the closest, with more than 150,000 asteroids in our solar system, “for which the instrument calculated its orbit with incomparable accuracy,” says Maynard, to new measurements related to more than 1.8 billion stars the Milky Way. And beyond this galaxy: clusters of other distant galaxies and quasars.
Launched by the European Space Agency (ESA), Gaia has been in operation since 2013, and is located in a privileged place, called L2, a million and a half kilometers from Earth, facing the Sun.
– clear the sky –
“Gaia scans the sky and captures everything she sees,” says astronomer Misha Haywood at the Paris-PSL Observatory. It detects and observes a very small fraction (barely 1%) of the stars in our galaxy, which are 100,000 light-years away.
But it draws more than just a map. Its two telescopes are connected to a billion-pixel photo sensor, with millions of commercial cameras. Three instruments of astronomy, photometry and spectroscopy, will interpret and later recover photons and real light signals.
“Thanks to this, it provides a global tracking of the positions of what is moving in the sky. This is the first time “, Mr. Haywood continues. Before Gaia,” we had a very limited view of the galaxy. “
before Gaia? It was Hipparcos, the satellite that revolutionized observation after its launch by the European Space Agency in 1997, cataloging more than 110,000 celestial bodies.
With Gaia, astronomers can access not only the positions and motions of a large number of stars, but also the measurements of their physical and chemical characteristics, and their ages are just as important.
Astronomer Paula Di Matteo, a colleague of Misha Haywood at the Paris-PSL Observatory, explains much of the information “which tells us about its past evolution and therefore the evolution of the galaxy.”
– great discoveries –
This is also “one of the reasons why Gaia is being built,” the astronomer continued. “Stars have the peculiarity of life for billions of years. So measuring them is like measuring a fossil that tells us about the state of the galaxy at the time of its formation. “
This overview of the movements of the stars in the Milky Way has already led to great discoveries. With the second catalog, delivered in 2018, astronomers were able to show that our galaxy “merged” with ours ten billion years ago.
The catalog has generated thousands of academic articles since its first edition in 2016. François explains that the data flow requires a dedicated terrestrial processing chain, DPAC, which calls supercomputers for six European computer centers and mobilizes 450 specialists. Maynard, the person in charge.
“Without this processing suite, there is no task,” because Gaia produces 700 million stellar sites, 150 million photometers and 14 million spectra every day. A torrent of raw data, which “human-driven” algorithms turn into measurements that astronomers can use.
It will take five years to deliver this third catalog of observations from 2014 to 2017. And we will have to wait until 2030 for the final version, when Gaia will finish scanning the space, in 2025.