Unveiling a map of 1.8 billion stars in the Milky Way

Map showing the 3D motion of 26 million stars in the Milky Way. The blue region shows the average velocity of the stars towards Earth, the red region the average velocity away. The lines represent the movement of the stars in the plane of space. (Photo: ESA/Gaia/DPAC)

The European Space Agency (ESA) on June 13 announced the third dataset of Gaia - the observatory launched into space in 2013 with the goal of "galactic inventory" and the most comprehensive 3D mapping. from the past to the Milky Way. The new dataset updates information on about 1.8 billion stars, including their structures and motions, as well as statistics on stellar earthquakes, binary star systems, variable stars and many other objects other.

Gaia's first large data set was published in 2016, listing the luminosity and positions of 1.1 billion stars. In 2018, the second dataset shows the coordinates of nearly 1.7 billion stars and the motions of 1.3 billion of them. In 2020, part of a third dataset will be released, helping to chart the motion of the solar system around the galactic center.

Now, ESA has released the full third Gaia dataset of about 1.8 billion stars with information on chemical composition, temperature, color, mass, age, motion, and classification. Of which, 1.5 billion stars have been specifically classified.

The third dataset also includes new spectral information gathered by splitting stellar light into its constituent colors, done at low resolution with 470 million stars and at high resolution with 5, 6 million stars. This allows scientists to determine factors such as their temperature, mass, age, color, metallicity and chemical composition.

As a result, they discovered that stars near the galactic center are often more metallic than stars at the outer edges. This helps experts understand more about stellar evolution in different regions, because heavy metals are created and distributed as old stars die, and then integrate into newly born stars. from ashes.

Map of the metallicity of stars in the Milky Way, from low metal content (blue) to high metal content (red).

Gaia also demonstrated the ability to detect earthquakes in thousands of stars as large-scale oscillations occur on their surfaces. Interestingly, this phenomenon occurs on many stars that scientists did not expect earthquakes, raising new questions.

The new dataset also calculates the radial velocities of 33 million stars, a measure of how quickly a star is moving towards or away from Earth. This information adds a third dimension to the map of star motion, rather than just showing how they move across the plane of space.

In addition, Gaia identified about 10 million stars that are changing in brightness over time, and 813,000 star systems containing two stars orbiting each other. This represents the largest census of variable stars and binary systems ever recorded.

Gaia also collected information on 156,000 asteroids and 31 moons in the Solar System. In addition to the Milky Way, the dataset contains information about 2.9 million other galaxies, including their brightness, color, shape, history of star formation, and information about 1.9 million quasars, including redshift, brightness, color.

The newly published extensive dataset will be extremely useful to future astronomers. They can use these findings to explore science in a variety of ways.