New Gaia data provides the most detailed view of the Milky Way to date

New Gaia data provides the most detailed view of the Milky Way to date

New Gaia data provides the most detailed view of the Milky Way to date

1.6 billion stars. 11.4 million galaxies. 158,000 asteroids.

A spacecraft.

Launched in 2013, the European Space Agency’s Gaia space observatory has long surpassed its goal of mapping more than a billion stars in the Milky Way (SN: 15/10/16)† On June 13, the mission expanded that map into new dimensions, releasing more detailed measurements of hundreds of millions of stars, plus — for the first time — asteroids, galaxies and the dusty medium between stars.

“Suddenly you have a deluge of data,” said Laurent Eyer, an astrophysicist at the University of Geneva who spent years working on Gaia. For some topics in astronomy, the new results actually replace any observations made before, Eyer says. “The data is better. It is awesome.”

Data in the new study, collected from 2014 to 2017, is already leading to some discoveries, including the presence of surprisingly massive “starquakes” on the surfaces of thousands of stars (SN: 8/2/19† But above all, the release is a new resource for astronomers, one that will help them understand how stars, planets and entire galaxies form and evolve.

Here are some of the long-standing puzzles the data can help solve.

asteroid hodgepodge

The asteroid belt between Mars and Jupiter is a mess of history. After the Earth and other planets formed, the rocky building blocks that were left smashed together, leaving jumbled fragments behind. But if scientists know enough about individual asteroids, they can reconstruct where and when they came from (SN: 4/13/19)† And that could give a glimpse into the earliest days of the solar system.

Using new Gaia data, astronomers have plotted the June 13, 2022 positions of 156,000 asteroids. The trails show their orbits for the past 10 days, and the colors highlight different groups of asteroids based on their location (blue, inner solar system; green, the main asteroid belt between Mars and Jupiter; orange, the Trojan asteroids near Jupiter).DPAC/Gaia/ESA, CC BY-SA 3.0 IGO

Gaia’s massive new dataset could help solve this puzzle, said Federica Spoto, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. It contains data on the chemical composition of more than 60,000 asteroids – six times more than researchers had such details before using other tools. That information could be essential to trace asteroids back to their crushing origins.

“You can go back in time and try to understand all the formation and evolution of the solar system,” said Spoto, a Gaia collaborator.That’s something huge that we couldn’t even think of before Gaia.”

Asteroids aren’t just pieces of the past, though; they are also dangerous. The new data could reveal asteroids that are nearly impossible to see from Earth because they orbit too close to the sun, said Thomas Burbine, a planetary scientist at Mount Holyoke College in South Hadley, Massachusetts, who is not involved in the study. the mission (SN: 15/2/20)† Since these asteroids originally would have come from farther away (for example, the asteroid belt), they can tell us about the rocks that pass the Earth and could potentially hit us. “We’ll get to know our neighborhood better,” says Burbine.

Dating a star

It is notoriously difficult to measure the age of stars (SN: 23-7-21)† “It’s not uncommon to have uncertainty over a billion years,” said Alessandro Savino, an astrophysicist at the University of California, Berkeley who is not involved with Gaia. Unlike brightness or location, age is not immediately apparent. Astronomers must rely on theories about how stars evolve to predict ages based on what they can measure.

If previous versions of the Gaia research were like a picture of stars, the new release is like shifting the picture from black and white to color. It provides a deeper look at hundreds of millions of stars by measuring their temperature, gravity and chemistry. “You imagine the star as this point in space, but then they have so many properties,” Spoto says. “That’s what Gaia gives you.”

While these kinds of measurements are far from new, they have never been collected on such a scale in the Milky Way. That data could provide more insight into how stars evolve. “We can improve the resolution of our clocks,” says Savino.

Milky Way Snacks

While it may seem immutable, the Milky Way is actually eating a steady diet of smaller galaxies — it’s even eating one right now. But for decades, predictions about when and how these cosmic mergers will take place have been at odds with evidence from our galaxy, says Bertrand Goldman, an astrophysicist at the International Space University in Strasbourg, France, who is not involved in the publication of Gaia data. “That’s been controversial for a long time,” Goldman says, “but I think Gaia will definitely shed light.”

The key is to be able to take apart different structures in the Milky Way and see how old they are (SN: 1/10/20)† Gaia’s latest release helps in two ways: by mapping the chemistry of stars and by measuring their motion. Earlier versions of the study described how millions of stars moved, but mostly in two dimensions. The new catalog quadruples the number of stars with full 3D trajectories from 7 million to 33 million.

This has consequences beyond our neighbourhood. Most of the mass in the universe is in galaxies like the Milky Way, so knowing how our own galaxy works can help us understand space on the largest scales. And the more scientists understand the parts of galaxies they can see, the more they can learn about dark matter, the mysterious substance that exerts gravity but doesn’t interact with light (SN: 25/6/21)

Even as astronomers mine this latest dataset, they are already looking ahead to future treasure hunts. The next round is in a few years, but it is expected to enable the discovery of thousands of exoplanets, produce rare measurements of black holes and help astronomers determine how fast the Universe is expanding. In part, this is because Gaia is designed to track the movement of objects in space, and that becomes easier the more time passes. So Gaia’s perceptions can only become more powerful. “Like fine wine, they age very, very well,” Savino says.