the discoveries of the most detailed map of the Milky Way to date

The Gaia mission of the European Space Agency (ESA) has today published a new, more detailed map of our galaxy. Astronomers describe strange 'stellar earthquakes', stellar DNA, asymmetrical motions and other 'fascinating' data in this most detailed study of the Milky Way to date. a press release.

Gaia is ESA's mission to create the most accurate and comprehensive multidimensional map of the Milky Way. This allows astronomers to reconstruct the structure of our galaxy and its past evolution over billions of years, and to better understand the life cycle of stars and our place in the Universe.

What's new in version 3 of the data?

Version 3 of the Gaia data contains new and improved details on nearly two billion stars in our galaxy. The catalog includes new information, such as chemical compositions, stellar temperatures, colors, masses, ages, and the rate at which stars are moving toward or away from us.

Much of this information has been revealed by new data from spectroscopy, a technique in which starlight is split into its constituent colors (like a rainbow). The data also includes special subsets of stars, such as those that change brightness over time.

Gaia is opening up a gold mine for 'astroseismology' of massive stars

Conny Aerts — Catholic University of Leuven

This dataset also includes the largest catalog of binary stars, thousands of Solar System objects such as asteroids and moons of planets, and millions of galaxies and quasars outside the Milky Way.

stellar earthquakes

One of the most surprising discoveries to emerge from the new data is that Gaia is capable of detecting stellar earthquakes – small movements on the surface of a star – that change the shape of stars, something the observatory was not originally built to do. .

Previously, Gaia had already found radial oscillations that cause stars to periodically swell and shrink, maintaining their spherical shape. But now Gaia has also detected other vibrations that are more like large-scale 'tsunamis'. These non-radial oscillations change the overall shape of a star and are therefore more difficult to detect.

Gaia found strong non-radial stellar vibrations in thousands of stars. Gaia also revealed these kinds of vibrations in stars that had rarely been seen before. These stars should not register any 'earthquakes' according to current theory, while Gaia did detect them on its surface.

“Starquakes teach us a lot about stars, especially about their inner workings. Gaia is opening up a gold mine for 'astroseismology' of massive stars,” Conny Aerts, from the Catholic University of Leuven, Belgium, who is a member of the Gaia collaboration, says in the ESA press release.

The DNA of the stars

The composition of the stars allows us to know their place of birth and their subsequent trajectory and, therefore, the history of the Milky Way. With today's data release, Gaia reveals the largest chemical map of the galaxy, from our solar neighborhood to the smaller galaxies surrounding our own.

Some stars contain more "heavy metals" than others. During the 'Big Bang', only light elements (hydrogen and helium) were formed. All the other heavier elements – called metals by astronomers – form inside stars. When stars die, they release these metals into the gas and dust between them, called the 'interstellar medium', from which new stars form. The active formation and death of stars leads to a more metal-rich environment. Therefore, the chemical composition of a star is a bit like its DNA, which gives us crucial information about its origin.

With Gaia, the press release continues, we see that some stars in our galaxy are made of primordial material, while others, like our Sun, are made of matter enriched by earlier generations of stars. Stars closer to the center and plane of our galaxy are richer in metals than stars further away. Gaia also identified stars that originally came from galaxies other than our own, based on their chemical composition.

"Our galaxy is a beautiful melting pot of stars," says Alejandra Recio-Blanco of the Observatory de la Côte d'Azur, France, who is a member of the Gaia collaboration. “This diversity is extremely important, because it tells us the story of the formation of our galaxy. It reveals the processes of migration within our galaxy and accretion from external galaxies. It also clearly shows that our Sun, and us, belong to an ever-changing system, formed by the assembly of stars and gas of different origins."

Binary stars, asteroids, quasars and more

Other papers being published today reflect the breadth and depth of Gaia's potential for discovery. A new binary star catalog presents the mass and evolution of more than 800,000 binary systems, while a new study of asteroids comprising 156,000 rocky bodies is delving deeper into the origin of our Solar System. Gaia is also revealing information about 10 million variable stars, mysterious macromolecules between stars, as well as quasars and galaxies beyond our own cosmic neighborhood.

Binary stars, asteroids, quasars and more

Other papers being published today reflect the breadth and depth of Gaia's potential for discovery. The new binary star catalog presents the mass and evolution of more than 800,000 binary systems, while a new study of asteroids including 156,000 rocky bodies delves into the origin of our Solar System. Gaia is also revealing information about 10 million variable stars, mysterious macromolecules between stars, as well as quasars and galaxies beyond our own cosmic neighborhood.

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