The Gaia mission, whose space telescope is mapping the galaxy in detail, on Monday unveiled a new news release of nearly two billion stars that have tracked their path and analyzed their properties.
“It’s the Swiss knife of astrophysics. “There is not a single astronomer who does not use his data directly or indirectly,” the C Εte d’Ivoire astronomer told AFP. France.
The astronomy community will be able to draw from Monday, from 10:00 GMT, on the third list of data collected by the instrument. Harvest, accompanied by about fifty scientific articles, 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 involving more than 1.8 billion stars. of our Galaxy. And beyond this galaxy: groups of other galaxies and distant quasars.
Launched on behalf of the European Space Agency (ESA), Gaia has been operating since 2013 and is located in a privileged location, called L2, one and a half million kilometers from Earth, facing the Sun.
– clear the sky –
“Gaia is scanning the sky and recording everything it sees,” astronomer Misha Haywood told the Paris-PSL Observatory. It detects and observes a very small fraction (only 1%) of the stars in our galaxy, which are 100,000 light-years in diameter.
But he designs more than just a map. Its two telescopes are connected by a multibillion-pixel photographic sensor, with commercial cameras numbering in the millions. Three astronomical instruments, photometry and spectroscopy, will interpret and then retrieve real photons and light signals.
“Thanks to this, it provides global monitoring of the positions of what is moving in the sky. “This is the first time.” 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, recording more than 110,000 celestial bodies.
With Gaia, astronomers can access not only the positions and movements of a large number of stars, but also the measurements of their physical and chemical characteristics, while their age is just as important.
Astronomer Paula Di Matteo, a colleague of Misha Haywood at the Paris-PSL Observatory, explains much of the information “that tells us about their past evolution, and therefore about the evolution of the galaxy”.
– important discoveries –
This is also “one of the reasons why Gaia was built,” the astronomer continued. “Stars have the peculiarity of life for billions of years. Thus, 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 Galaxy has already led to important discoveries. With the second list, delivered in 2018, astronomers were able to show that our galaxy “merged” with ours another ten billion years ago.
The catalog has generated thousands of scholarly articles since its first publication in 2016. François explains that the flow of data requires an exclusive terrestrial processing chain, DPAC, which calls supercomputers for six European computing centers, mobilizing 450 specialists. Maynard, who was in charge.
“Without this editing suite there is no work,” because Gaia produces 700 million stellar locations, 150 million photometers and 14 million spectra every day. A torrent of raw data, which “human guidance” algorithms translate into measurements that astronomers can use.
It will take five years for this third list of observations to be delivered from 2014 to 2017. And we will have to wait until 2030 for the final version, when Gaia will complete the site scan in 2025.
