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New Star Map Could Change Everything We Know About the Milky Way

The map includes 1.7 billion stars and is already revealing new details about star evolution and the formation of our galaxy

Gaia's all-sky view of our Milky Way Galaxy and neighboring galaxies, based on measurements of nearly 1.7 billion stars. (ESA/Gaia/DPAC)

In 2016, the European Space Agency released the first data set from its Gaia satellite, which is tasked with surveying stars to create a detailed 3-D map of our quadrant of the Milky Way. Over 1 billion stars twinkled in those first images, which included detailed data on 2 million of the stars. Today, ESA released an even more mind-blowing batch of Gaia data encompassing 1.7 billion stars including incredible detail on almost every speck of light.

As Ryan F. Mandelbaum at Gizmodo reports, compared to the initial survey, which included stars some 500 light years away, the latest round of data includes twinkles as far as 8,000 light years out, with a precision 100 times more accurate. Gaia surveyed the sky for 22 months between July 2014 and May 2016 to gather the new dataset.

According to the ESA, the catalog, now available to professionals and amateur astronomers, includes data on the positions and brightness for 1.7 billion stars, the parallax (an effect in which an object appears in different positions depending the viewer’s position) and motion of 1.3 billion stars, surface temperature for over 100 million stars and the effect of interstellar dust on 87 million stars.

The data also covers other objects as well, including the positions of 14,000 asteroids in our solar system and the positions of half a million quasars outside the Milky Way. According to the ESA, researchers were also able to plot the orbits of 75 globular clusters—or groups of stars held together by gravity— within our galaxy and 12 dwarf galaxies orbiting the Milky Way.

“Gaia is an unprecedented map of the Milky Way galaxy, fundamental astrophysics at its finest, laying the groundwork for decades of research on everything from the solar system to the origin and evolution of the universe,” astronomer Emily Rice of CUNY College of Staten Island and the American Museum of Natural History tells Mandelbaum. “It is at once foundational and transformative, which is rare in modern astronomy.”

The charts were not just automatically generated. It took years for some 450 human scientists and software engineers to analyze the raw satellite data and produce the 3-D star charts, asteroid orbits and other images, the Associated Press reports.

And the data has already led to some breakthroughs. Antonella Vallenari, one of the lead scientists on the project, tells the AP that the results seems to support a hypothesis that the Milky Way was once hit with material from another galaxy, creating ripples evidenced by stars that move in ways different than expected.

A close look at 4 million stars has also refined something known as the Hertzsprung-Russell diagram, which uses the color and magnitude of stars to determine their evolutionary stage. The diagram has already helped researchers learn to distinguish white dwarfs dominated by hydrogen and white dwarfs dominated by helium. It also suggests that the stars in the disc and halo of the Milky Way are different ages, suggesting there were two galactic formation events.

As Nola Taylor Redd at Scientific American reports, the data should also help astronomers study the mysterious brown dwarfs, perplexing failed stars that are not quite planets and not quite stars. Studying brown dwarfs can teach researchers a lot about both star and planet formation. “It’s like being handed everything you ever wanted to know about brown dwarfs,” Jackie Faherty, a brown dwarf researcher at the American Museum of Natural History, told Redd prior to the release of the data.

This is just a tiny preview of what’s to come. “The combination of all these unprecedented measures provides the information for astronomers to take the next big steps in mapping the formation history and evolutions of stars and our Milky Way Galaxy,” University of Cambridge’s Gerry Gilmore, one of the primary Gaia investigators, says in the press release. “There is hardly a branch of astrophysics which will not be revolutionized by Gaia data…we anticipate new science papers appearing every day after this release.”

Uwe Lammers, the Gaia operations manager tells Deutsche Welle that by the end of its five-year mission in 2019, Gaia will have surveyed each star 70 times. While the third data dump in 2020 won’t add many stars to the catalog, it will produce even finer detail. As Mandelbaum reports, the release will include spectral data on the stars which will add a whole new level of information.

Just to keep things in perspective: Gaia’s map of 1.7 billion stars is just a tiny fraction of the 100 billion (or more) estimated to exist in the Milky Way. Just imagine what we could learn if we mapped them all.

About Jason Daley

Jason Daley is a Madison, Wisconsin-based writer specializing in natural history, science, travel, and the environment. His work has appeared in Discover, Popular Science, Outside, Men’s Journal, and other magazines.

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