The European Space Agency (ESA) just released the most precise and detailed map of the stars in our galaxy to date: a 3D map of over a billion stars, including observations about their temperature, luminosity, and chemical composition.

A collection like no other

The Gaia mission was launched in 2013 with the goal of conducting a “galactic census” — mapping the stars in the galaxy in the most comprehensive possible way.

The first major data release came in 2016, detailing the brightness and location of 1.1 billion stars. In 2018, the second data release came in, and now, the third data release features data on a whopping 1.8 billion stars. In addition, the dataset also features millions of other objects such as galaxies and quasars outside the Milky Way, as well as over 150,00 asteroids in the Solar System. The finding “revolutionizes our understanding of the galaxy,” the European Space Agency (ESA) said.

“Our galaxy is a beautiful melting pot of stars,” says Alejandra Recio-Blanco of the Observatoire de la Côte d’Azur in France, who is a member of the Gaia collaboration. 

“This diversity is extremely important, because it tells us the story of our galaxy’s formation. It reveals the processes of migration within our galaxy and accretion from external galaxies. It also clearly shows that our Sun, and we, all belong to an ever changing system, formed thanks to the assembly of stars and gas of different origins.”

The catalog features multiple types of data, which means it can be used by astronomers working in different fields to understand the evolution of stars in our galaxy (and stars in general). The catalog includes data that can be used to infer the stars’ age and mass, their radial velocity (the speed at which they’re moving away from Earth), and even their temperature.

“Unlike other missions that target specific objects, Gaia is a survey mission. This means that while surveying the entire sky with billions of stars multiple times, Gaia is bound to make discoveries that other more dedicated missions would miss. This is one of its strengths, and we can’t wait for the astronomy community to dive into our new data to find out even more about our galaxy and its surroundings than we could’ve imagined,” says Timo Prusti, Project Scientist for Gaia at ESA.

Much of this new information comes from spectroscopy data, a technique that images the different wavelengths of light coming from stars. Thanks to this type of data, we can see that some stars in our galaxy are made from primordial material, while others (like our Sun) are made from recycled star material.

Surprisingly, the Gaia data was shown to also be able to detect starquakes. Somewhat like the quakes here on Earth, stars can experience oscillations. These movements are more like tsunamis inside the star that produce slight changes on the surface of the star — and they can be used to infer certain parameters about the star’s structure. This field of research is called asteroseismology, mirroring the field of seismology, which uses seismic waves to infer properties about the Earth’s subsurface.

“Starquakes teach us a lot about stars, notably their internal workings. Gaia is opening a goldmine for ‘asteroseismology’ of massive stars,” says Conny Aerts of KU Leuven in Belgium, who is a member of the Gaia collaboration.

It’s hard to emphasize just how massive this dataset is. To mention just a few things, the dataset includes a new asteroid survey comprising 156 thousand rocky bodies, some of which have been around since the dawn of the solar system; information about 10 million variable stars; data on 800,000 binary star systems; and mysterious molecules that seem to form between some stars.

Other papers that are published today reflect the breadth and depth of Gaia’s discovery potential. A new binary star catalog presents the mass and evolution of more than 800 thousand binary systems, while other parts of the set offer information that could help us peer deeper into the origin of our Solar System. Gaia is also revealing information about 10 million variable stars, mysterious macro-molecules between stars, as well as quasars and galaxies beyond our own cosmic neighborhood.

More details on Gaia’s data releases 3 can be found here: https://www.cosmos.esa.int/web/gaia/data-release-3 

From 13 June 2022, 12:00 CEST onwards, the new Gaia data can be accessed at https://gea.esac.esa.int/archive/