Star movements, chemical composition, asteroids … Here are five new pictures of what our Milky Way looks like

Today at 10.00 The Gaia mission of the European Space Agency (ESA) released its “new collection of data” about the galaxy we live in. Gaia is the mission to create the most accurate and comprehensive multidimensional map of the Milky Way. Thanks to this space telescope, launched in 2013, astronomers have the opportunity to reconstruct the structure of our galaxy and its past evolution over billions of years and to better understand the life cycle of stars as well as our place in the universe. .

Specifically, Gaia, among other things, tries to know as much as possible about more than 2 billion stars orbiting the center of our galaxy.

The third Gaia data catalog contains new and improved details for these two billion stars in the Milky Way. Among this new information: chemical compositions, star temperatures, colors, masses, ages, and the speed at which stars approach or move away from us (radial velocity).

We also find the largest catalog of binary stars to date (a third of the stars are born and live in pairs or even larger groups), thousands of solar system objects such as asteroids and planetary satellites, as well as beyond the Milky Way, millions of galaxies for example or the strange quasars. These brightest objects in the universe hold supermassive black holes in their hearts that tear stars that pass within their reach.

One of the most startling findings from the new data is that Gaia is able to detect star tremors – small movements on a star’s surface – that change the shape of the stars, something the Gaia Observatory is unable to do. It was not originally designed. “Starquakes teaches us a lot about stars, including their inner workings. Gaia opens a gold mine for ‘asteroseismology’ of massive stars,” says Conny Aerts, astrophysicist at KU Leuven in Belgium, a member of the Gaia Collaboration, like many other scientists from Belgian universities , which has also processed and analyzed the vast amounts of data provided by the Gaia satellite.

© ESA / Gaia / DPAC, CC BY-SA 3.0 IGO.

The composition of stars can tell us about their place of birth and their subsequent journey, and therefore about the history of the Milky Way. With today’s data catalog, Gaia brings us a chemical map of the galaxy. Some stars actually contain more “heavy” elements than others. During the Big Bang, only light elements (hydrogen and helium) were formed. All other heavier elements – called metals by astronomers – are built inside stars. When stars die, they release these metals into the gas and dust between the stars, called the interstellar medium from which new stars form. The formation and death of active stars will lead to a more metallic environment. Therefore, the chemical composition of a star is very similar to its DNA, giving us crucial information about its origin.

This view of the entire sky above shows a sample of the stars in the Milky Way in the 3rd Gaia data catalog. The color indicates the metallicity of the stars. Redder stars are richer in metals.

With Gaia, we see that some stars in our galaxy are made of primordial matter, while others like our sun are made of matter enriched by previous generations of stars. Stars closer to the center and planet of our galaxy are richer in metals than stars at greater distances.

Star movements, chemical composition, asteroids ... Here are five new pictures of what our Milky Way looks like
© ESA / Gaia / DPAC, CC BY-SA 3.0 IGO.

ESA’s third Gaia data catalog shows us how quickly more than 30 million Milky Way objects (mostly stars) approach or move away from us. This is called “radial velocity”. We can now see with this image how objects move across a large part of the Milky Way’s disk.

The rotation of the disk, projected along the line of sight, is visible at the alternation between light zones (moving away from us) and dark zones (moving towards us). Several objects whose radial velocity differs from their immediate surroundings are visible in contrast.

The large and small Magellanic clouds, two dwarf galaxies (LMC and SMC), appear as bright areas in the lower right corner of the image. The Sagittarius dwarf galaxy is visible as a faint, almost vertical band beneath the galactic center.

Several globular clusters (very dense clusters of stars) appear as tiny dots in the image, such as 47 Tucanae, the dark dot immediately to the left of the SMC.

Star movements, chemical composition, asteroids ... Here are five new pictures of what our Milky Way looks like
© ESA / Gaia / DPAC, CC BY-SA 3.0 IGO.

This sky map shows the velocity field of about 26 million stars in the Milky Way. The colors represent the radial velocities of the stars along the line of sight. Blue indicates the parts of the sky where the average motion of the stars is toward us, and red indicates the areas where the average motion is away from us. The lines visible in the figure trace the motion of the stars projected in the sky (correct motion). These lines show how the direction of star velocity varies with galactic latitude and longitude. The large and small Magellanic clouds (LMC and SMC) are not visible because only stars with well-defined distances have been selected for this image.

Star movements, chemical composition, asteroids ... Here are five new pictures of what our Milky Way looks like
© ESA / Gaia / DPAC, CC BY-SA 3.0 IGO.

Not only does it map the stars in our galaxy, but the Gaia mission also tells us what lies between the stars. The space between stars is not empty, but instead filled with clouds of dust and gas from which stars are born.

Thanks to the precise measurements of star positions and their scattered light, Gaia makes it possible to map the absorption of star light by the interstellar medium. These maps give us important clues about the physical mechanisms of star formation, galaxies, and the history of our home galaxy.

This map above shows the interstellar dust that fills the Milky Way. The dark areas in the center of the galactic plane in black are areas with lots of interstellar dust that fade to yellow as the amount of dust decreases. The dark blue areas above and below the galactic plane are areas with little dust.

Star movements, chemical composition, asteroids ... Here are five new pictures of what our Milky Way looks like
© ESA / Gaia / DPAC, CC BY-SA 3.0 IGO.

This image shows the orbits of more than 150,000 asteroids in the new Gaia catalog, from the inner parts of the solar system to the Trojan asteroids at Jupiter’s distance, with different color codes

The yellow circle in the middle represents the Sun. Blue describes the inner part of the solar system, where terrestrial asteroids, Mars cruisers and terrestrial planets are found. The main belt, between Mars and Jupiter, is green. Jupiter’s Trojan horses are red.

“Unlike other missions that target specific objects, Gaia is an exploration mission. This means that by exploring the entire sky many times with billions of stars, Gaia is committed to making discoveries that” Other more dedicated missions would miss. It is one of its strengths, and we can not wait for the astronomical community to dive into our new data to learn even more about our galaxy and its surroundings than we could have ever imagined, “says Timo Prusti, project researcher for Gaia at ESA.

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