Gaia offers an unparalleled map of the Milky Way

France Press agency , Posted on Saturday, June 11, 2022 at 4:23 pm

The Gaia mission, whose space telescope maps the Milky Way in detail, on Monday unveiled an informative new version of the nearly two billion stars that have traced their path and analyzed properties.

“It’s the Swiss army knife of astrophysics. There is not a single astronomer who will not use his data directly or indirectly,” the astronomer from the Côte d’Ivoire told AFP. France.

The community of astronomers will be able to draw starting Monday, from 10:00 GMT, on the third catalog of data collected by the instrument. Harvest, accompanied by some fifty scholarly articles, lists an array 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 Mr. Maynard, to new measurements relating to more than 1.8 billion stars of the Milky Way. And beyond this galaxy: groups of other galaxies and distant quasars.

Launched on behalf of the European Space Agency (ESA), Gaia has been in operation since 2013, and is stationed in a privileged location, called L2, one and a half million kilometers from Earth, opposite the Sun.

– clear the sky –

“Gaia scans the sky and captures everything it sees,” sums up 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 across.

But it draws more than a simple map. Its two telescopes are linked to a billion-pixel photographic sensor, with commercial cameras numbering in the millions. Three astronomy instruments, photometry and spectroscopy, will interpret, and subsequently retrieve, real photons and light signals.

“Thanks to this, it provides global monitoring of the positions of what moves in the sky. This is the first time,” continues Mr. Haywood. 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 movements of a large number of stars, but also measurements of their physical and chemical characters, 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 “that tells us about their past evolution, and thus about the evolution of the galaxy.”

– major discoveries –

This is also “one of the reasons why Gaia is built,” continued the astronomer. “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 motions of the Milky Way’s stars has already led to major discoveries. With the second catalog, delivered in 2018, astronomers were able to show that our galaxy “merged” with ours another ten billion years ago.

The catalog has spawned thousands of scholarly articles since its first edition in 2016. François explains that data flow requires a dedicated terrestrial processing chain, DPAC, that calls supercomputers for six European computing centers, mobilizing 450 specialists. Maynard, who was responsible.

“Without this processing suite there is no task,” because Gaia produces 700 million stellar sites, 150 million photometers, and 14 million spectra each day. A torrent of raw data, which “human-led” algorithms convert into measurements that astronomers can use.

It will take five years to deliver this third catalog of observations from 2014 to 2017. And it will be necessary to wait until 2030 for the final version, when Gaia will finish scanning the space, in 2025.