Gaia is an ESA mission that aims to create the most accurate and complete multidimensional map of Milky Way. This allows astronomers to reconstruct the structure and past evolution of our galaxy over billions of years, as well as better understand the life cycle of stars and our place in the universe.
As of December 2020, an early version of third dice roll (Early data release 3 or EDR3) from Gaia and this Monday the definitive version (DR3) of this third installment, which includes unpublished and improved information from almost 2 billion stars of our galaxy. The catalog incorporates new information, including chemical compositions, temperatures, colors, masses, ages, and the speed at which stars are approaching or moving away from us (radial velocity).
Much of this information comes from new data from spectroscopy now published, a technique in which starlight is split into its component colors (like a rainbow). In addition, the data includes special subsets of stars, such as those that change brightness over time.
Another novelty in this dataset is the largest catalog to date of binary stars, thousands of objects in the solar system, such as asteroids and the moons of the planets, and millions of galaxies and quasars located outside the Milky Way.
stellar earthquakes
One of the most surprising discoveries made from this new data is that Gaia can detect stellar earthquakes (small movements recorded on the surface of a star) that change the shape of stars, something the observatory was not originally designed to detect.
Gaia had previously encountered radial oscillations that caused stars to periodically wax and wane while maintaining their spherical shape. But now it has also detected other vibrations that can be considered as large scale tsunami. These non-radial oscillations change the star’s overall shape and are therefore more difficult to detect.
Mission managers have discovered powerful non-radial stellar earthquakes in thousands of stars. Gaia has also detected these vibrations in stars where they have rarely been seen before. Although these stars should not register any earthquakes according to current theory, the spacecraft detected them on their surface.
“Starquakes give us a lot of information about stars, especially about their inner workings. Gaia opens a gold mine for asteroseismology of massive stars”, explains one of the members of the Gaia collaboration, Conny Aertsfrom Ku Leuven University in Belgium.
The DNA of the Stars
The composition of stars can tell us about their birthplace and subsequent trajectory, and therefore about the history of the Milky Way. With the publication of the data this Monday, Gaia presents the biggest chemical map of our galaxy along with 3D motions, ranging from our solar neighborhood to the smaller galaxies that surround our own.
Some stars contain more heavy metals than others. During the Big Bang, only light elements (hydrogen and helium) were formed. The heaviest, the metals, are created inside stars, and when they die, they release them into the gas and dust we find in the interstellar medium, from which new stars are formed. The active formation of stars and their death allow the existence of a richer environment in metals. So a star’s chemical makeup is somewhat similar to its DNA and gives us crucial information about its origin.
Thanks to Gaia, we see that some stars in our galaxy are composed of primordial material, while others, like our Sun, contain enriched matter from previous generations of stars. Those closer to the center and plane of our galaxy are richer in metals compared to stars located farther away. Gaia has 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,” he explains. Alejandra Recio-Blanco, member of the Gaia collaboration at the Observatoire de la Côte d’Azur in France. “And this diversity is extremely important, as it tells us the story of the formation of our galaxy. Reveals processes of migration within our galaxy and accretion [crecimiento por adición de materia] of outer galaxies. It also clearly shows that our Sun and we all belong to an ever-changing system, formed thanks to the encounter of stars and gases of different origins.”
Binary Stars, Asteroids and Quasars
Other articles also being published now reflect the breadth and depth of Gaia’s discoveries. A new binary star catalog presents the mass and evolution of more than 800,000 binary systems, while other work on asteroids comprising 156,000 rocky bodies investigates the origin of our solar system.
Gaia also reveals information about 10 million variable stars and mysterious macromolecules among stars, as well as about quasars and galaxies located beyond our own cosmic neighborhood.
“Unlike other object-focused quests, Gaia is a search or astronomical survey. This means that during regular surveys of the entire sky with billions of stars, Gaia will make discoveries that more specialized missions could not. It’s one of your strengths. We can’t wait to see how the astronomical community delves into our new data to learn more about our galaxy and its environment than we could ever have imagined.” Timo PrustyGaia project scientist at ESA.